null-terminated string
A NULL-terminated string is a sequence of characters that ends with a character of 0. This is the standard string in C. Example:
"Hello" is a 6 byte string, where the 5 visible characters are followed by a 0. In memory, things look as follows: (Using hex representation) 48 65 6C 6C 6F 00
The null termination is expected by all string related routines in the C-standard library, such as strlen, strcpy.