Final answer:
A 'string index out of range' error means trying to access a part of a string that doesn't exist. This usually happens in programming when the index being accessed is beyond the length of the string.
Step-by-step explanation:
When you receive an error stating string index out of range, it indicates that you are attempting to access a position within a string that does not exist. In many programming languages, strings are treated as arrays of characters, where each character has an index starting from 0. For example, in the string "Hello", the index of 'H' is 0, and the index of 'o' is 4.
If you tried to access a character at index 5 (which would be the sixth character, since indexing starts at zero), you would get a string index out of range error because there is no sixth character in the word "Hello". This error is a common mistake that can occur when looping through strings or accessing characters by an incorrect index value.