20 surprising things you didn't know about 'Big Brother'

• "Big Brother" has been on the air for 19 years.
• "Big Brother" also has a "Celebrity Big Brother" spinoff in the US and UK.
• There are almost a hundred cameras watching every houseguest.

Ever since "Big Brother" first locked away a group of people (called houseguests) in a house for the summer and called it reality TV, people have been tuning in to see all the drama unfold in real time.

Airing three times a week on TV, the CBS show is actually on all the time thanks to a set of cameras and microphones that pick up contestant behavior 24 hours a day, seven days a week, and stream it live to audiences online.

Fans can watch the houseguests eat, cook, and sleep — and strategize, of course. This is a competition show, after all.

It’s both oddly relaxing to watch strangers just live their lives, and thrilling to watch the twists and turns during competitions.

But with 19 years and 20 seasons under its belt, even the biggest of superfans can’t know everything there is to know about this show.

Here are 20 surprising facts you probably didn’t know about this summer reality TV staple.

SEE ALSO: 16 surprising facts you didn't know about 'Survivor'

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It’s actually based on a Dutch show.

CBS adapted the Dutch reality show’s format when it started gathering big ratings in Germany and Spain as well, according to SF Gate.

It’s been adapted to a ton more countries too.

"Big Brother" has taken place in India, Australia, Brazil, the UK, Africa, Italy, Saudi Arabia, Canada, and more, according to ET Canada.

The contestants get paid.

Unlike on many other reality shows, CBS pays its houseguests for taking the summer off for the show. According to a reported "Big Brother" contract obtained by Reality Blurred, contestants make $750 per week for as long as they’re still in the game.