1st person and 3rd person narrative

I would use 1st person to bring out a main character, particularly his thoughts and feelings. Also, it can be used to give a different point of view on another main character, such as in The Great Gatsby and Sherlock Holmes. It is also used to bring you closer to the story, as it feels as if the characters are talking and interacting with you through the first person.

3rd person, however, can be used to describe setting as in third person you can see all. It can also bring out the relationship between characters as you know what every single one of the characters are doing and thinking.