diff --git a/src/main/java/com/example/springhw32/controller/CommentController.java b/src/main/java/com/example/springhw32/controller/CommentController.java
index 0ee065d..b67d55a 100644
--- a/src/main/java/com/example/springhw32/controller/CommentController.java
+++ b/src/main/java/com/example/springhw32/controller/CommentController.java
@@ -1,5 +1,27 @@
 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.*;
+
+import java.util.List;
+
+@RestController
+@RequiredArgsConstructor
+@RequestMapping("/posts")
 public class CommentController {
+    private final CommentService commentService;
+
+    //댓글 작성
+    @PostMapping("/comments")
+    public CommentDto addComment(@ModelAttribute CommentDto commentDto, @RequestParam Long postId) {
+        return commentService.addComment(commentDto, postId);
+    }
 
+    //특정 게시물에 달린 모든 댓글 조회
+    @GetMapping("/comments/postid")
+    public List<CommentDto> getCommentByPostId(@PathVariable Long postId) {
+        return commentService.getCommentByPostId(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..1956a70 100644
--- a/src/main/java/com/example/springhw32/controller/PostController.java
+++ b/src/main/java/com/example/springhw32/controller/PostController.java
@@ -1,5 +1,40 @@
 package com.example.springhw32.controller;
 
+import com.example.springhw32.dto.PostDto;
+import com.example.springhw32.service.PostService;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@RestController
+@RequiredArgsConstructor
+@RequestMapping("/posts")
 public class PostController {
+    private final PostService postService;
+
+    //글작성
+    @PostMapping("")
+    public PostDto save(@ModelAttribute PostDto postDto, Long userId) {
+        return postService.save(postDto, userId);
+    }
+
+    //최신순으로 글 조회
+    @GetMapping("")
+    public List<PostDto> findAllByOrderByCreatedAtDesc() {
+        return postService.findAllByOrderByCreatedAtDesc();
+    }
+
+    //작성자 글 조회
+    @GetMapping("/{writer}")
+    public List<PostDto> findAllByWriter(@PathVariable("writer") Long userId) {
+        return postService.findAllByWriter(userId);
+    }
 
+    //댓글 많은 순 조회
+    @GetMapping("/comments")
+    public List<PostDto> findAllByOrderByCommentNumberDesc() {
+        return postService.findAllByOrderByCommentNumberDesc();
+    }
 }
diff --git a/src/main/java/com/example/springhw32/controller/UserController.java b/src/main/java/com/example/springhw32/controller/UserController.java
index 3b321ac..b1a2814 100644
--- a/src/main/java/com/example/springhw32/controller/UserController.java
+++ b/src/main/java/com/example/springhw32/controller/UserController.java
@@ -1,5 +1,20 @@
 package com.example.springhw32.controller;
 
-public class UserController {
+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;
 
+@RestController
+@RequiredArgsConstructor
+public class UserController {
+    private final UserService userService;
+    //회원가입
+    @PostMapping("/users")
+    public UserDto signup(@ModelAttribute UserDto userDto) {
+        return userService.signup(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..725cc43 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;
 
-public class CommentDto {
+import com.example.springhw32.entity.Post;
+import lombok.Getter;
+import lombok.Setter;
 
+@Getter
+@Setter
+public class CommentDto {
+    private String text;
 }
diff --git a/src/main/java/com/example/springhw32/dto/PostDto.java b/src/main/java/com/example/springhw32/dto/PostDto.java
index cde1eda..58cd75c 100644
--- a/src/main/java/com/example/springhw32/dto/PostDto.java
+++ b/src/main/java/com/example/springhw32/dto/PostDto.java
@@ -1,5 +1,16 @@
 package com.example.springhw32.dto;
 
-public class PostDto {
+import com.example.springhw32.entity.User;
+import lombok.Getter;
+import lombok.Setter;
+
+import java.time.LocalDateTime;
 
+@Getter
+@Setter
+public class PostDto {
+    private String title;
+    private String content;
+    private LocalDateTime createdAt;
+    private int commentNumber;
 }
diff --git a/src/main/java/com/example/springhw32/dto/UserDto.java b/src/main/java/com/example/springhw32/dto/UserDto.java
index cbbbe2e..f71ccd4 100644
--- a/src/main/java/com/example/springhw32/dto/UserDto.java
+++ b/src/main/java/com/example/springhw32/dto/UserDto.java
@@ -1,5 +1,11 @@
 package com.example.springhw32.dto;
 
-public class UserDto {
+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..dda7ff4 100644
--- a/src/main/java/com/example/springhw32/entity/Comment.java
+++ b/src/main/java/com/example/springhw32/entity/Comment.java
@@ -1,5 +1,21 @@
 package com.example.springhw32.entity;
 
+import jakarta.persistence.*;
+import lombok.Getter;
+import lombok.Setter;
+import org.apache.catalina.users.GenericRole;
+
+@Entity
+@Getter
+@Setter
 public class Comment {
 
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long Id;
+
+    @ManyToOne
+    private Post post;
+
+    private String text;
 }
diff --git a/src/main/java/com/example/springhw32/entity/Post.java b/src/main/java/com/example/springhw32/entity/Post.java
index 38b5e81..b108bcb 100644
--- a/src/main/java/com/example/springhw32/entity/Post.java
+++ b/src/main/java/com/example/springhw32/entity/Post.java
@@ -1,5 +1,30 @@
 package com.example.springhw32.entity;
 
+import jakarta.persistence.*;
+import lombok.Getter;
+import lombok.Setter;
+
+import java.time.LocalDateTime;
+
+@Entity
+@Getter
+@Setter
 public class Post {
 
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long Id;
+
+    @ManyToOne
+    private User user;
+
+    @Column(nullable = false)
+    private String title;
+
+    @Column(nullable = false)
+    private String content;
+
+    private int commentNumber;
+
+    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..7274db0 100644
--- a/src/main/java/com/example/springhw32/entity/User.java
+++ b/src/main/java/com/example/springhw32/entity/User.java
@@ -1,5 +1,21 @@
 package com.example.springhw32.entity;
 
+import jakarta.persistence.*;
+import lombok.Getter;
+import lombok.Setter;
+
+@Entity
+@Getter
+@Setter
 public class User {
 
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long Id;
+
+    @Column(nullable = false, unique = true)
+    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..321fd87 100644
--- a/src/main/java/com/example/springhw32/repository/CommentRepository.java
+++ b/src/main/java/com/example/springhw32/repository/CommentRepository.java
@@ -1,5 +1,10 @@
 package com.example.springhw32.repository;
 
-public interface CommentRepository {
+import com.example.springhw32.entity.Comment;
+import org.springframework.data.jpa.repository.JpaRepository;
 
+import java.util.List;
+
+public interface CommentRepository extends JpaRepository<Comment, Long> {
+    public List<Comment> findAllByPostId(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..5fe63f2 100644
--- a/src/main/java/com/example/springhw32/repository/PostRepository.java
+++ b/src/main/java/com/example/springhw32/repository/PostRepository.java
@@ -1,5 +1,12 @@
 package com.example.springhw32.repository;
 
-public interface PostRepository {
+import com.example.springhw32.entity.Post;
+import org.springframework.data.jpa.repository.JpaRepository;
 
+import java.util.List;
+
+public interface PostRepository extends JpaRepository<Post, Long> {
+    public List<Post> findAllByOrderByCreatedAtDesc();
+    public List<Post> findAllByUserId(Long userId);
+    public List<Post> findAllByOrderByCommentNumberDesc();
 }
diff --git a/src/main/java/com/example/springhw32/repository/UserRepository.java b/src/main/java/com/example/springhw32/repository/UserRepository.java
index 877a215..ae8c6b0 100644
--- a/src/main/java/com/example/springhw32/repository/UserRepository.java
+++ b/src/main/java/com/example/springhw32/repository/UserRepository.java
@@ -1,5 +1,9 @@
 package com.example.springhw32.repository;
 
-public interface UserRepository {
+import com.example.springhw32.entity.User;
+import org.springframework.data.jpa.repository.JpaRepository;
 
+import java.util.Optional;
+
+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..afd4e73 100644
--- a/src/main/java/com/example/springhw32/service/CommentService.java
+++ b/src/main/java/com/example/springhw32/service/CommentService.java
@@ -1,5 +1,47 @@
 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 java.util.List;
+import java.util.stream.Collectors;
+
+@Service
+@RequiredArgsConstructor
 public class CommentService {
+    private final CommentRepository commentRepository;
+    private final PostRepository postRepository;
+
+    //댓글 작성
+    public CommentDto addComment(CommentDto commentDto, Long postId) {
+        Post post = postRepository.findById(postId).orElseThrow();
+
+        Comment comment = new Comment();
+        comment.setPost(post);
+        comment.setText(commentDto.getText());
+        commentRepository.save(comment);
+
+        post.setCommentNumber(post.getCommentNumber() + 1);
+        postRepository.save(post);
+
+        return commentDto;
+    }
+
+    //특정 개시물에 달린 모든 댓글 조회
+    public List<CommentDto> getCommentByPostId(Long postId) {
+        List<CommentDto> commentDtos = commentRepository.findAllByPostId(postId).stream()
+                .map(this::EntityToDto).collect(Collectors.toList());
+        return commentDtos;
+    }
 
+    private CommentDto EntityToDto(Comment comment) {
+        CommentDto commentDto = new CommentDto();
+        commentDto.setText(comment.getText());
+        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..07cc2e0 100644
--- a/src/main/java/com/example/springhw32/service/PostService.java
+++ b/src/main/java/com/example/springhw32/service/PostService.java
@@ -1,5 +1,63 @@
 package com.example.springhw32.service;
 
+import com.example.springhw32.dto.PostDto;
+import com.example.springhw32.entity.Post;
+import com.example.springhw32.repository.PostRepository;
+import com.example.springhw32.repository.UserRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.web.bind.annotation.PostMapping;
+
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Service
+@RequiredArgsConstructor
 public class PostService {
+    private final PostRepository postRepository;
+    private final UserRepository userRepository;
+
+    //글 작성
+    public PostDto save(PostDto postDto, Long userId) {
+        Post post = new Post();
+        post.setTitle(postDto.getTitle());
+        post.setContent(postDto.getContent());
+        post.setUser(userRepository.findById(userId).orElse(null));
+        post.setCommentNumber(0);
+        post.setCreatedAt(LocalDateTime.now());
+        postRepository.save(post);
+        return postDto;
+    }
+
+    //최신순으로 글 조회
+    public List<PostDto> findAllByOrderByCreatedAtDesc() {
+        List<PostDto> postDtos = postRepository.findAllByOrderByCreatedAtDesc().stream()
+                .map(this::EntityToDto).collect(Collectors.toList());
+        return postDtos;
+    }
+
+    //특정 회원이 작성한 글 조회
+    public List<PostDto> findAllByWriter(Long userId) {
+        List<PostDto> postDtos = postRepository.findAllByUserId(userId).stream()
+                .map(this::EntityToDto).collect(Collectors.toList());
+        return postDtos;
+    }
+
+    //댓글이 많은 순으로 정렬 조회
+    public List<PostDto> findAllByOrderByCommentNumberDesc() {
+        List<PostDto> postDtos = postRepository.findAllByOrderByCommentNumberDesc().stream()
+                .map(this::EntityToDto).collect(Collectors.toList());
+        return postDtos;
+    }
 
+    private PostDto EntityToDto(Post post) {
+        PostDto postDto = new PostDto();
+        postDto.setTitle(post.getTitle());
+        postDto.setContent(post.getContent());
+        postDto.setCreatedAt(post.getCreatedAt());
+        postDto.setCommentNumber(post.getCommentNumber());
+        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..6672aef 100644
--- a/src/main/java/com/example/springhw32/service/UserService.java
+++ b/src/main/java/com/example/springhw32/service/UserService.java
@@ -1,5 +1,23 @@
 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;
+
+@Service
+@RequiredArgsConstructor
 public class UserService {
 
+    private final UserRepository userRepository;
+    //회원가입
+    public UserDto signup(UserDto userDto) {
+        User user = new User();
+        user.setUsername(userDto.getUsername());
+        user.setPassword(userDto.getPassword());
+        userRepository.save(user);
+        return userDto;
+    }
+
 }
diff --git a/src/main/resources/application.yml b/src/main/resources/application.yml
index 9b78d0c..5f39bc2 100644
--- a/src/main/resources/application.yml
+++ b/src/main/resources/application.yml
@@ -1,8 +1,8 @@
 spring:
   datasource:
-    url: jdbc:mysql://localhost:3306/your_database_name?useSSL=false&serverTimezone=UTC&characterEncoding=UTF-8
-    username: your_username
-    password: your_password
+    url: jdbc:mysql://localhost:3306/demo?useSSL=false&serverTimezone=UTC&characterEncoding=UTF-8
+    username: root
+    password: na58745874@
     driver-class-name: com.mysql.cj.jdbc.Driver
 
   jpa: