[FAQ] What should I wear to a job interview?

This thread is apart of the FAQ Hosting thread. Please help us make it better by answering the question in the Post's title.

Feel free for answers to also address:

• What should be worn for to an interview.
• What are the pros/cons to being over dressed?
• What are the pros/cons to being under dressed?
• If the job requires wearing casual clothes, is it alright to show up in casual clothes?