Houston has two major airports: George Bush Intercontinental Airport (IAH), 15 miles northeast of downtown, and Hobby Airport (HOU), 9 miles southeast of the city. Taxis and shuttles are available into town from the airports, but it’s probably best just to rent a car, which you’ll most likely need to get around Houston during your stay.
Unfortunately, a car is a must if you want to really explore Houston. There are walkable areas (Midtown, Neartown/Montrose, and Downtown), but access from those neighborhoods to the rest of the city by public transportation is quite limited. The light rail is called METRO and runs 7.5 miles from Reliant Park to the University of Houston-Downtown.