Public transport is based upon a fairly dense network of tramway and bus lines operated by two companies, supplemented by a number of private minibus operators. An easy way to determine if a bus is municipal, or not, is to check its paint scheme, white, blue and navy or wholly yellow. Each has its own, non-transferable,  ticket.
Tickets can be bought in many different places from the ticket selling machines  placed on bus/tram stations, and several important stops, most of them the centre. Another way is to buy the ticket after boarding the bus/tram, from a ticket automaton or from the driver with an additional fee (now it is PLN 0,50 for a ticket). Also many kiosks, newspaper and tobacco shops sell tickets.

For students who have a Euro 26 or an ISIC card, there is a discount. Special tickets for them are called “ulgowy gminny” (“communal, discounted (ticket)”) and cost PLN 1,35.

While planning how to get from one place to another, you may find this tool useful:
mpkoogle