Explain the concept of extensions in Spring Boot and their role in applications.

In Spring Boot, extensions (starters, auto-configuration, custom starters) help simplify and accelerate application development by automatically configuring and connecting necessary components.

• Starters — sets of dependencies for specific functions (e.g., spring-boot-starter-web for web applications).
• Auto-configuration automatically configures beans and components based on the libraries and settings present in the classpath.
• Custom extensions allow developers to create their own extension modules for reuse and integration.

The role of extensions is to minimize manual configuration, increase modularity, and simplify the integration of third-party libraries into the application.