Let's start with a simple pom.xml file with spring-boot-starter-parent:

    <project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
     http://maven.apache.org/xsd/maven-4.0.0.xsd">   
    <modelVersion>4.0.0</modelVersion> 
    <groupId>com.mastering.spring</groupId> 
    <artifactId>springboot-example</artifactId> 
    <version>0.0.1-SNAPSHOT</version> 
    <name>First Spring Boot Example</name> 
    <packaging>war</packaging>
    <parent> 
      <groupId>org.springframework.boot</groupId> 
      <artifactId>spring-boot-starter-parent</artifactId>  
      <version>2.0.0.M1</version>
    </parent>
    <properties> 
      <java.version>1.8</java.version> 
    </properties>
 
   <repositories>
    <repository>
      <id>spring-milestones</id>
      <name>Spring Milestones</name>
      <url>https://repo.spring.io/milestone</url>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
    </repository>
   </repositories>

   <pluginRepositories>
    <pluginRepository>
      <id>spring-milestones</id>
      <name>Spring Milestones</name>
      <url>https://repo.spring.io/milestone</url>
        <snapshots>
          <enabled>false</enabled>
        </snapshots>
     </pluginRepository>
    </pluginRepositories>

</project>

The first question is this: why do we need spring-boot-starter-parent?

A spring-boot-starter-parent dependency contains the default versions of Java to use, the default versions of dependencies that Spring Boot uses, and the default configuration of the Maven plugins.

Let's look at some of the code inside spring-boot-starter-parent to get a deeper understanding about spring-boot-starter-parent.