HyperText Markup Language (HTML) is the main markup language for web pages. HTML elements are the basic building-blocks of webpages. wikipedia.org

Cascading Style Sheets (CSS) is a style sheet language used to describe the presentation (that is, the look and formatting) of a document written in a markup language. wikipedia.org

Mobile application testing is a process by which application software developed for hand held mobile devices is tested for its functionality, usability and consistency. wikipedia.org

Software testing is an investigation conducted to provide stakeholders with information about the quality of the product or service under test. wikipedia.org

Quality Assurance (QA) is a way of preventing mistakes or defects in manufactured products and avoiding problems when delivering solutions or services to customers.

Manual testing is the process of manually testing software for defects. It requires a tester to play the role of an end user, and use most of all features of the application to ensure correct behavior. wikipedia.org