A null character is a special character in computer programming that represents the end of a string. It is often denoted as `'\0'` in languages like C and C++. This character is essential for string manipulation, as it helps functions determine where a string ends, preventing errors and memory issues. In many programming languages, the null character is used to signify that there are no more characters to read in a sequence. It plays a crucial role in data structures like arrays and linked lists, ensuring that operations on strings and data are performed correctly and efficiently.