Sanity testing:

Once a new build is obtained with minor revisions, instead of doing a through regression, a sanity is performed so as to ascertain the build has indeed rectified the issues and no further issue has been introduced by the fixes. Its generally a subset of regression testing and a group of test cases are executed that are related with the changes made to the app.

Generally, when multiple cycles of testing are executed, sanity testing may be done during the later cycles after through regression cycles.

A sanity test is a narrow regression test that focuses on one or a few areas of functionality. Sanity testing is usually narrow and deep.

A Sanity test is used to determine a small section of the application is still working after a minor change.

Sanity testing is a cursory testing; it is performed whenever a cursory testing is sufficient to prove the application is functioning according to specifications. This level of testing is a subset of regression testing.

sanity testing is to verify whether requirements are met or not,

checking all features breadth-first.