At its most basic level, the Army consists of squads of soldiers. With anywhere from four to 16 soldiers, and led by either a sergeant or staff sergeant, it takes three to four squads to form a platoon. At this level, a 1st or 2nd lieutenant (not so affectionately referred to as commissioned privates) is in command, often with the help of a platoon sergeant (usually a sergeant first class).
Things scale up from here, with three to four platoons or 100 to 200 soldiers constituting a company, often with a captain in command. Gather up three to five companies, and you'll end up with a battalion, while three battalions form a brigade. In the former, a lieutenant colonel is in command, while in the latter, it's a full-bird colonel.
Now we're getting into the really big units. Three brigades forms a division, which usually consists of 10,000 to 18,000 soldiers, while a corps includes anywhere from two to five divisions. According to the Army's website, putting two to five corps will form a field army. At this level, only generals are in command, with a major general (two stars) at the division level, a lieutenant general (three stars) at the corps level and a four-star general at the field army level.
As with anything in the military, the variety here is very nearly limitless. There are different names for different units based on their function, such as section, troop and regiment, making it difficult for us to break them all down here. Even the numbers listed fluctuate based on a units function. That said, this basic listing should provide a basic knowledge of the Army's groupings, so you won't be fully in the dark the next time you hear about a local unit on the news.
If you have any suggestions on a phrase you aren't sure about, be sure to reach out to brandon dot turkus at autoblog dot com, and we'll be sure to feature it in the coming days.