That's an extremely broad question/statement. What do you want to know? You will want to start off with the 2018 IBC (International Building Code) as well as 780 CMR (Massachusetts amendments to the IBC). Your local Building Department will also be a good resource to answer code related questions. They are a free resource. If you have a very in depth or complicated question, then you may have to get an Architect involved.
@Daniel Weber I am trying to see if I can place a bathroom and exercise room in the basement of a 3 family house, I wanted to find the code that regulates that thanks
So basements in MA need to have 50% of the square footage above ground. Most of this you see with multis on a hill so one side is a walk out. I have never done any finished space in basements but know that part of the code. As long as there are no bedrooms I think you may be able to do this, a quick call to the building department could clear this up they are usually helpful answering these specific types of questions.