Simplify the following text for a Grade 9 native English-speaking person.
Original: Outside the cue sports industry , pocket billiards is ( in English ) more commonly referred to as pool , due to perhaps an association with the poolrooms where gamblers pooled their money to bet off-track on horse races .
Simplified: Outside the billiards industry , the various games played on these tables are very often called `` pool '' . This is due to an association with the `` poolrooms '' where gamblers `` pooled '' together their money to bet on horse races .