A character counter is a tool that helps people with different languages count the number of characters they have written in a text. Character counters can be accessed through many online platforms, but it is also available for download for those that are more into the technical aspect of things. The character counter will tell you how many words are present, as well as how many letters are in your text. Character counters would count all spaces, punctuations, letters, numbers, etc.
A string is a series of letters, numbers, or other characters grouped together to form a word or sentence. The length of a string can be found by counting all of the characters in it.