system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What the hell is going on when you see the actors credited as 'Executive Producers' in a TV show?

I'm watching the new season of House of Cards.

Robin Wright is listed on her own as 'Executive Producer'. The next credit is Kevin Spacey along with someone else as 'Executive Producers'.

The US Office comedy also listed lot of the actors as executive producers. I know Mindy Kaling, B.J. Novak and Paul Lieberstein (Toby the sad HR guy) were writers more than actors, but the main cast got those credits too. 

**Is it just extra cash? Are there different jobs that get lumped under this title and is there a hierarchy?**
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EDIT: *The question is specifically about television.* Writing, production and the use of titles including 'Executive Producer' is different from cinema. Hell I know this, even though I am five years old. If your answer relates to cinema or blurs the distinction it might be misleading.
gpt
It's usually written into their contract - down to the size of the font and placement on the 'card' and even whether it stands alone or is under or above someone else's credit. It can vary from contract to contract in terms of what it really means for a person's paycheck; in some cases (certain movies, for example) it might mean that a person has invested some of their own money into a project. It's a form of ownership really.  

Basically - it can mean many, many things.