A "C String" is a sequence of characters used in the programming language C. It is represented as an array of characters terminated by a null character (`'\0'`). This null character indicates the end of the string, allowing functions to determine its length and content. C Strings are commonly used for handling text in C programs. They can be manipulated using various standard library functions, such as strlen for measuring length and strcpy for copying strings. Understanding C Strings is essential for effective programming in C, as they are fundamental to text processing and data handling.