Hexadecimal is a base-16 number system that uses sixteen distinct symbols: the digits 0-9 and the letters A-F. In this system, A represents 10, B represents 11, C represents 12, D represents 13, E represents 14, and F represents 15. Hexadecimal is commonly used in computing and digital electronics because it can represent large binary numbers in a more compact and readable form. For example, the binary number 1111 1111 can be easily expressed as FF in hexadecimal. This makes it simpler for programmers and engineers to work with memory addresses and color codes in web design, where colors are often represented in the format #RRGGBB, with RR, GG, and BB being hexadecimal values.