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).