Testing types

Explain a.)Upward Compression testing b.)Usability Testing c.)Gray box testing d.)Structural Testing e.) Reliability Testing

a.)Upward Compression testing
Upward compression testing is testing the compression of a subordinate module into a superior module when de-modularization is done.
b.)Usability Testing
Usability testing focuses on how usable the product is and is generally performed by the actual users who will be using the product. This technique is generally used for web and mobile applications where usability is of high importance.
c.)Gray box testing
Gray box testing is combination of white and black box testing wherein the tester is required to know little understanding of the program's internal logic and will verify the functionality of the program based on the understanding.
d.)Structural Testing
Structural testing technique uses structural or internal perspective of the system to design test cases and carry execution. They are also called as white box or clear box testing.
e.) Reliability Testing
Reliability testing is testing for the software's reliability which is checking if the program performs its intended function with required precision as expected.

Differentiate between smoke testing and sanity testing.

-Smoke testing verifies all areas of application; sanity testing verifies one or few areas only.
-Smoke testing is done before accepting code for testing - Sanity testing is a subset of regression testing and is used whenever it is sufficient to prove that the application is working as per requirements.