Or, in the US Army, the guidon bearer (pronounced "guide-on"). First position in the right file.

The US Army currently uses four squads of ten people each for a platoon: two fire teams (or sections), one of 5 and one of 4, plus the squad leader. Three "rifle" or work platoons, plus a headquarters platoon of varying size, make up a company. Four companies to a battalion.

Usually. Sections can be added or subtracted, special missions can do special things, etc.