To build a spring boot application you need different dependencies (many lol) a spring boot starter project will provide you with many starter dependencies and help you get your project to work out of the box. There are different starters for different purposes e.g. web app needs the web app starter project
in a nutshell a spring boot starter project is a dependency descriptor for various features
- web app & rest api: spring boot starter web
- unit test: spring boot starter test
- talk to database using jpa: spring boot starter data jpa
- talk to database using jdbc: spring boot starter jdbc
- secure your web app or rest api: string boot starter security