A hexadecimal number is a number expressed using the base-16 number system. It is often used in computing for its compact representation of binary data. Hexadecimal numbers use 16 distinct symbols including 0-9 and A-F, where A-F represent the values 10-15. They are also commonly referred to as hex numbers. Each digit in a hexadecimal number can be thought of as representing 4 bits in binary.
Hexadecimal numbers are closely related to binary numbers because each digit in a hexadecimal number can be represented by a group of 4 bits in binary. This means that a hexadecimal number can be easily converted to binary by simply replacing each digit with its 4 bit representation.