Your gateway to Prague is through Ruzyne International Airport; the airport is a hub for Czech Airlines, the flag carrier of the Czech Republic. It's accessible via bus and taxi when travelling within Prague.
If you want to fly low-cost airlines offering extensive flights to Prague, you can choose from easyJet, a U.K. carrier and Sky Europe, a Czech carrier. You can also choose other budget-fare airlines, but these have limited Prague flights: namely Ryanair, Jet2.com, and bmibaby, all of them U.K. carriers.
Most major airlines offer economy class and premium economy class flights to and from Prague.