This document discusses different types of constants in C programming. It defines constants as fixed values that do not change during program execution. There are several types of constants including numeric, character, and string constants. Numeric constants can be integer, real, octal, or hexadecimal values. Integer constants do not contain decimal points while real constants can be written in decimal or exponential notation. Character constants contain a single character within single quotes and string constants contain a sequence of characters within double quotes. The document provides examples and details for each constant type.