Bialystok isn't big so we have only ... buses.There are many of them so you can get every where. You can buy disposable ticket or for one month (which is cheaper for those who use buses every day). If you want to check how many buses we have and how do they look like, you can visit the side http://www.komunikacja.bialystok.pl/
Buses are not very comfortable and fast so for those who are in a hurry and don't have a car there are cabs. The cabs aren't yellow. Bialystok's cabs are different cars. We have many cab's companies but the most popular are : 9191 and 9626 (those numbers are telephone numbers).
HEre in Barcelona most people use underground or buses, but we have kept other means of transport.
ResponEliminaTaxis here are not very cheap and street are often packed with cars, on the other hand there's a stron movement trying to use public transport intead of private, or walk or cycling... due to CO2 emissions.