diff --git a/.gitignore b/.gitignore
index c2065bc..a04fa92 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,6 +22,7 @@ bin/
 *.iws
 *.iml
 *.ipr
+*.yml
 out/
 !**/src/main/**/out/
 !**/src/test/**/out/
diff --git a/src/main/java/com/example/springhw32/controller/CommentController.java b/src/main/java/com/example/springhw32/controller/CommentController.java
index 0ee065d..6cf81a9 100644
--- a/src/main/java/com/example/springhw32/controller/CommentController.java
+++ b/src/main/java/com/example/springhw32/controller/CommentController.java
@@ -1,5 +1,34 @@
 package com.example.springhw32.controller;
 
+import com.example.springhw32.dto.CommentDto;
+import com.example.springhw32.service.CommentService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.ModelAttribute;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.List;
+
+@RequestMapping("/posts/comments")
+@RestController
+@RequiredArgsConstructor
 public class CommentController {
 
+    private final CommentService commentService;
+
+    // 댓글 작성
+    @PostMapping
+    public CommentDto createComment(@ModelAttribute CommentDto commentDto, @RequestParam Long postId) {
+        return commentService.createComment(commentDto, postId);
+    }
+
+    // 특정 게시물에 달린 모든 댓글 조회
+    @GetMapping("/{postId}")
+    public List<CommentDto> findAllByPostId(@PathVariable Long postId) {
+        return commentService.findAllByPostId(postId);
+    }
 }
diff --git a/src/main/java/com/example/springhw32/controller/PostController.java b/src/main/java/com/example/springhw32/controller/PostController.java
index 317774b..06fd209 100644
--- a/src/main/java/com/example/springhw32/controller/PostController.java
+++ b/src/main/java/com/example/springhw32/controller/PostController.java
@@ -1,5 +1,44 @@
 package com.example.springhw32.controller;
 
+import com.example.springhw32.dto.PostDto;
+import com.example.springhw32.service.PostService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.ModelAttribute;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.List;
+
+@RequestMapping("/posts")
+@RestController
+@RequiredArgsConstructor
 public class PostController {
+    private final PostService postService;
+
+    // 글 작성
+    @PostMapping
+    public PostDto createPost(@ModelAttribute PostDto postDto, Long userId) {
+        return postService.createPost(postDto, userId);
+    }
+
+    // 최신순 글 조회
+    @GetMapping
+    public List<PostDto> finaAllByCreatedAtDesc() {
+        return postService.finaAllByCreatedAtDesc();
+    }
+
+    // 작성자 글 조회
+    @GetMapping("/{writer}")
+    public List<PostDto> findAllByUsername(@PathVariable("writer") String username) {
+        return postService.findAllByUsername(username);
+    }
 
+    // 댓글 많은 순 글 조회
+    @GetMapping("/comments")
+    public List<PostDto> findAllByOrderByCommentCountDesc() {
+        return postService.findAllByOrderByCommentCountDesc();
+    }
 }
diff --git a/src/main/java/com/example/springhw32/controller/UserController.java b/src/main/java/com/example/springhw32/controller/UserController.java
index 3b321ac..bfe4671 100644
--- a/src/main/java/com/example/springhw32/controller/UserController.java
+++ b/src/main/java/com/example/springhw32/controller/UserController.java
@@ -1,5 +1,24 @@
 package com.example.springhw32.controller;
 
+import com.example.springhw32.dto.UserDto;
+import com.example.springhw32.service.UserService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.ModelAttribute;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RequestMapping("/users")
+@RestController
+@RequiredArgsConstructor
 public class UserController {
 
+    private final UserService userService;
+
+    // 회원가입
+    @PostMapping
+    public UserDto join(@ModelAttribute UserDto userDto) {
+        return userService.join(userDto);
+    }
 }
+
diff --git a/src/main/java/com/example/springhw32/dto/CommentDto.java b/src/main/java/com/example/springhw32/dto/CommentDto.java
index a9d04fa..2c525ee 100644
--- a/src/main/java/com/example/springhw32/dto/CommentDto.java
+++ b/src/main/java/com/example/springhw32/dto/CommentDto.java
@@ -1,5 +1,11 @@
 package com.example.springhw32.dto;
 
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
 public class CommentDto {
 
+    private String content;
 }
diff --git a/src/main/java/com/example/springhw32/dto/PostDto.java b/src/main/java/com/example/springhw32/dto/PostDto.java
index cde1eda..b67f5d0 100644
--- a/src/main/java/com/example/springhw32/dto/PostDto.java
+++ b/src/main/java/com/example/springhw32/dto/PostDto.java
@@ -1,5 +1,20 @@
 package com.example.springhw32.dto;
 
+import lombok.Getter;
+import lombok.Setter;
+
+import java.time.LocalDateTime;
+
+@Getter
+@Setter
 public class PostDto {
 
+    private String title;
+
+    private String content;
+
+    private Long commentCount;
+
+    private LocalDateTime createdAt;
+
 }
diff --git a/src/main/java/com/example/springhw32/dto/UserDto.java b/src/main/java/com/example/springhw32/dto/UserDto.java
index cbbbe2e..18119bc 100644
--- a/src/main/java/com/example/springhw32/dto/UserDto.java
+++ b/src/main/java/com/example/springhw32/dto/UserDto.java
@@ -1,5 +1,14 @@
 package com.example.springhw32.dto;
 
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
 public class UserDto {
 
+    private String username;
+
+    private String password;
+
 }
diff --git a/src/main/java/com/example/springhw32/entity/Comment.java b/src/main/java/com/example/springhw32/entity/Comment.java
index be818a0..0d3184d 100644
--- a/src/main/java/com/example/springhw32/entity/Comment.java
+++ b/src/main/java/com/example/springhw32/entity/Comment.java
@@ -1,5 +1,28 @@
 package com.example.springhw32.entity;
 
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+import lombok.Getter;
+import lombok.NonNull;
+import lombok.Setter;
+
+@Getter
+@Setter
+@Entity
 public class Comment {
 
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long CommentId;
+
+    @ManyToOne
+    private Post post;
+
+    @NonNull
+    private String content;
+
+
 }
diff --git a/src/main/java/com/example/springhw32/entity/Post.java b/src/main/java/com/example/springhw32/entity/Post.java
index 38b5e81..2d3b00f 100644
--- a/src/main/java/com/example/springhw32/entity/Post.java
+++ b/src/main/java/com/example/springhw32/entity/Post.java
@@ -1,5 +1,38 @@
 package com.example.springhw32.entity;
 
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+import lombok.Getter;
+import lombok.Setter;
+
+import java.time.LocalDateTime;
+
+@Getter
+@Setter
+@Entity
 public class Post {
 
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long postId;
+
+    @ManyToOne
+    private User user;
+
+    @Column(nullable = false)
+    private String title;
+
+    @Column(nullable = false)
+    private String content;
+
+    @Column(nullable = false)
+    private Long commentCount = 0L;
+
+    @Column(nullable = false)
+    private LocalDateTime createdAt;
+
 }
diff --git a/src/main/java/com/example/springhw32/entity/User.java b/src/main/java/com/example/springhw32/entity/User.java
index 447989d..8b80fca 100644
--- a/src/main/java/com/example/springhw32/entity/User.java
+++ b/src/main/java/com/example/springhw32/entity/User.java
@@ -1,5 +1,27 @@
 package com.example.springhw32.entity;
 
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import lombok.Getter;
+import lombok.NonNull;
+import lombok.Setter;
+
+@Getter
+@Setter
+@Entity
 public class User {
 
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+
+    @Column(unique = true, nullable = false)
+    private String username;
+
+    @Column(nullable = false)
+    private String password;
+
 }
diff --git a/src/main/java/com/example/springhw32/repository/CommentRepository.java b/src/main/java/com/example/springhw32/repository/CommentRepository.java
index 83dcd99..6f12be3 100644
--- a/src/main/java/com/example/springhw32/repository/CommentRepository.java
+++ b/src/main/java/com/example/springhw32/repository/CommentRepository.java
@@ -1,5 +1,13 @@
 package com.example.springhw32.repository;
 
-public interface CommentRepository {
+import com.example.springhw32.entity.Comment;
+import com.example.springhw32.entity.Post;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
 
+import java.util.List;
+
+@Repository
+public interface CommentRepository extends JpaRepository<Comment,Long> {
+    List<Comment> findAllByPost_PostId(Long postId);
 }
diff --git a/src/main/java/com/example/springhw32/repository/PostRepository.java b/src/main/java/com/example/springhw32/repository/PostRepository.java
index 14b8546..df6cffa 100644
--- a/src/main/java/com/example/springhw32/repository/PostRepository.java
+++ b/src/main/java/com/example/springhw32/repository/PostRepository.java
@@ -1,5 +1,17 @@
 package com.example.springhw32.repository;
 
-public interface PostRepository {
+import com.example.springhw32.dto.PostDto;
+import com.example.springhw32.entity.Post;
+import org.hibernate.boot.archive.internal.JarProtocolArchiveDescriptor;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
 
+import java.util.List;
+
+@Repository
+public interface PostRepository extends JpaRepository<Post,Long> {
+
+    List<Post> findAllByOrderByCreatedAtDesc();
+    List<Post> findAllByUser_Username(String username);
+    List<Post> findAllByOrderByCommentCountDesc();
 }
diff --git a/src/main/java/com/example/springhw32/repository/UserRepository.java b/src/main/java/com/example/springhw32/repository/UserRepository.java
index 877a215..3e96a38 100644
--- a/src/main/java/com/example/springhw32/repository/UserRepository.java
+++ b/src/main/java/com/example/springhw32/repository/UserRepository.java
@@ -1,5 +1,13 @@
 package com.example.springhw32.repository;
 
-public interface UserRepository {
+import com.example.springhw32.entity.User;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.Optional;
+
+
+@Repository
+public interface UserRepository extends JpaRepository<User, Long> {
 
 }
diff --git a/src/main/java/com/example/springhw32/service/CommentService.java b/src/main/java/com/example/springhw32/service/CommentService.java
index ec0c937..db80a2c 100644
--- a/src/main/java/com/example/springhw32/service/CommentService.java
+++ b/src/main/java/com/example/springhw32/service/CommentService.java
@@ -1,5 +1,52 @@
 package com.example.springhw32.service;
 
+import com.example.springhw32.dto.CommentDto;
+import com.example.springhw32.entity.Comment;
+import com.example.springhw32.entity.Post;
+import com.example.springhw32.repository.CommentRepository;
+import com.example.springhw32.repository.PostRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Service
+@Transactional
+@RequiredArgsConstructor
 public class CommentService {
 
+    private final PostRepository postRepository;
+    private final CommentRepository commentRepository;
+
+    public CommentDto createComment(CommentDto commentDto, Long postId){
+        Post post = postRepository.findById(postId).orElseThrow();
+
+        Comment comment = new Comment();
+        comment.setContent(commentDto.getContent());
+        comment.setPost(post);
+        commentRepository.save(comment);
+
+        // 댓글 수 증가
+        post.setCommentCount(post.getCommentCount() + 1L);
+        postRepository.save(post);
+
+        return commentDto;
+    }
+
+    public List<CommentDto> findAllByPostId(Long postId){
+        return commentRepository.findAllByPost_PostId(postId).stream()
+                .map(this::convertToCommentDto)
+                .collect(Collectors.toList());
+    }
+
+
+    public CommentDto convertToCommentDto(Comment comment) {
+        CommentDto commentDto = new CommentDto();
+
+        commentDto.setContent(comment.getContent());
+
+        return commentDto;
+    }
 }
diff --git a/src/main/java/com/example/springhw32/service/PostService.java b/src/main/java/com/example/springhw32/service/PostService.java
index b029d55..29cb18d 100644
--- a/src/main/java/com/example/springhw32/service/PostService.java
+++ b/src/main/java/com/example/springhw32/service/PostService.java
@@ -1,5 +1,66 @@
 package com.example.springhw32.service;
 
+import com.example.springhw32.dto.PostDto;
+import com.example.springhw32.entity.Post;
+import com.example.springhw32.entity.User;
+import com.example.springhw32.repository.PostRepository;
+import com.example.springhw32.repository.UserRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.time.LocalDateTime;
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Service
+@Transactional
+@RequiredArgsConstructor
 public class PostService {
 
+    private final PostRepository postRepository;
+    private final UserRepository userRepository;
+
+    public PostDto createPost(PostDto postDto, Long userId){
+        User user = userRepository.findById(userId).orElseThrow();
+
+        Post post = new Post();
+        post.setUser(user);
+        post.setTitle(postDto.getTitle());
+        post.setContent(postDto.getContent());
+        post.setCreatedAt(LocalDateTime.now());
+        postRepository.save(post);
+
+        return postDto;
+    }
+
+    public List<PostDto> finaAllByCreatedAtDesc(){
+        return postRepository.findAllByOrderByCreatedAtDesc().stream()
+                .map(this::convertToPostDto)
+                .collect(Collectors.toList());
+    }
+
+    public List<PostDto> findAllByUsername(String username) {
+        return postRepository.findAllByUser_Username(username).stream()
+                .map(this::convertToPostDto)
+                .collect(Collectors.toList());
+    }
+
+    public List<PostDto> findAllByOrderByCommentCountDesc() {
+        return postRepository.findAllByOrderByCommentCountDesc().stream()
+                .map(this::convertToPostDto)
+                .collect(Collectors.toList());
+    }
+
+    public PostDto convertToPostDto(Post post) {
+        PostDto postDto = new PostDto();
+
+        postDto.setTitle(post.getTitle());
+        postDto.setContent(post.getContent());
+        postDto.setCommentCount(post.getCommentCount());
+        postDto.setCreatedAt(post.getCreatedAt());
+
+        return postDto;
+    }
+
 }
diff --git a/src/main/java/com/example/springhw32/service/UserService.java b/src/main/java/com/example/springhw32/service/UserService.java
index 8badccf..d4059b9 100644
--- a/src/main/java/com/example/springhw32/service/UserService.java
+++ b/src/main/java/com/example/springhw32/service/UserService.java
@@ -1,5 +1,26 @@
 package com.example.springhw32.service;
 
+import com.example.springhw32.dto.UserDto;
+import com.example.springhw32.entity.User;
+import com.example.springhw32.repository.UserRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@Transactional
+@RequiredArgsConstructor
 public class UserService {
 
+    private final UserRepository userRepository;
+
+    public UserDto join(UserDto userDto) {
+        User newUser = new User();
+        newUser.setUsername(userDto.getUsername());
+        newUser.setPassword(userDto.getPassword());
+
+        userRepository.save(newUser);
+        return userDto;
+    }
+
 }
diff --git a/src/main/resources/application.yml b/src/main/resources/application.yml
deleted file mode 100644
index 9b78d0c..0000000
--- a/src/main/resources/application.yml
+++ /dev/null
@@ -1,15 +0,0 @@
-spring:
-  datasource:
-    url: jdbc:mysql://localhost:3306/your_database_name?useSSL=false&serverTimezone=UTC&characterEncoding=UTF-8
-    username: your_username
-    password: your_password
-    driver-class-name: com.mysql.cj.jdbc.Driver
-
-  jpa:
-    hibernate:
-      ddl-auto: create
-    show-sql: true
-    properties:
-      hibernate:
-        format_sql: true
-        dialect: org.hibernate.dialect.MySQL8Dialect
\ No newline at end of file