What is the Spring Boot starter parent (POM) and how do you set up a Spring Boot 4 project?

<!-- Maven: spring-boot-starter-parent -->
<project>
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>4.1.0</version>  <!-- Spring Boot 4.1 (current) -->
        <relativePath/>
    </parent>

    <groupId>com.example</groupId>
    <artifactId>order-service</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <properties>
        <java.version>17</java.version>  <!-- minimum for Boot 4 -->
    </properties>

    <dependencies>
        <!-- Spring Boot 4 modular starters -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webmvc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>  <!-- includes JUnit 5 (Jupiter only in Boot 4) -->
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <!-- builds executable JAR with embedded Tomcat -->
            </plugin>
        </plugins>
    </build>
</project>