Question

Henry David Thoreau, often known as the father of environmentalism wrote the book entitled Walden.

Which revision should be made so that the sentence is properly punctuated

Answer 1

When adding on extra information to a thing or person, you put that information inside commas. For example:

Ultrilliam, the creator of QuestionCove, just recently changed his profile picture.

The subject is Ultrilliam, and we wanted to add that he is the creator of QuestionCove to clarify who we are talking about, so we put that inside commas. We would do the same for the sentence you provided. Do you have an idea of where the correction should be?