Jest is a popular JavaScript testing framework built on top of Jasmine, used by software engineers for unit testing. It supports projects using React, Babel, Vue, TypeScript, Node, Angular, and others. Jest includes a built-in mocking library, an assertion library, and tools to execute and debug unit tests. To set up Jest in an Angular project, you need to modify the `angular.json` file and install the necessary dependencies. The test suite is executed using the `ng test` command. Comprehensive unit tests ensure that your team can add new features, fix bugs, and reduce technical debt without breaking existing functionality. Jest requires minimal configuration for most JavaScript projects and allows engineers to write tests as they develop new features with minimal overhead. Its performant nature, parallelization, and ability to isolate tests make it a critical tool for Test-Driven Development (TDD). The Angular team is working on fully implementing Jest's features into the platform, allowing for code coverage analysis and automation of testing strategies.