Answer: Spell check
Spell check is a very useful tool available in the word processor application.
Step-by-step explanation:
It checks and verifies certain aspects like spelling, grammar, punctuation's etc.
When the user type a text in the word processor application, when there is a spelling error, the word automatically shows those in red, if there is a grammatical error then it underlines the text in green, similar way for the punctuation including the capitalization of the Starting letter after each line.
So this spell check function will be very helpful to do these literary aspects.