The bus or ‘colectivo’ system is extensive and massive, covering the city of Buenos Aires and the outer lying Province. Fares cost $1.10-$1.25, depending on the length of your ride; you will need to pay with coins (‘monedas’) but you don’t need the exact fare (the machines will dispense change). An exception is if you pay with a rechargeable balance card, i.e. the Monedero or SUBE, which most, but not all, buses accept; see the ‘Public Transportation’ overview for details.
To navigate the intricate colectivo system on your own, you’ll need the a Guia T (pronounced ‘teh’, not ‘tee’), which lists all of the 200+ routes along with maps of the city. You can purchase the pocket-sized edition for about $8 at most kioscos and newsstands. Because most of the streets in BsAs are one-way, you won’t have to worry about on which side of the street to catch the colectivo.
At the bus stop, people will stand single-file waiting patiently and politely to board. To flag a colectivo down, simply hold your arm out to signal to the driver. When boarding with several other people, it’s not uncommon for the bus driver to pull away from the stop with the doors still open. So when you get on, make sure you have a good foot hold or grip so you don’t fall off. Colectivos tend to stop every three or four blocks, and the stops are not clearly marked on any map; you just need to know in general where to get off. If you are unsure, ask the drivers: they are always willing to signal to you that they’re approaching your stop. There are buttons at the doors, and exiting passengers are supposed to leave through the doors in the middle or the back of the bus, not in front. If you don’t hear the bell ring when you push the button, fear not: the button signals a flashing light to the driver to pull over. Most drivers will not let you board or get off the bus unless it is a marked stop, so if you miss your exact destination don’t take it personally.
The fares are only for one ride and do not include transfers. You have to specify to the driver how much he should charge you for your ride, and most people simply give the price. If you are unsure, simply tell the driver your destination, or request the full fare of “uno veinticinco” or $1.25. Like in the Subtes, it is common practice for people to give up their seats for pregnant women, women with children, or older passengers. Don’t be alarmed if someone tells you to get up so that they can sit down; it’s not done rudely, just as a courtesy as it is assumed that you didn’t notice. The windows in the colectivos open, so feel free to open the one next to you to let air in – most buses are not equipped with air conditioning and can get quite hot in the summertime.
There is no website dedicated to the colectivo system because the lines are run by multiple private companies. However, a great site for planning your trip around the city is http://www.comoviajo.com. It will tell you where to catch the bus, when to get off, and where to transfer if need be.