On most audio interfaces you’ll typically find both XLR and 1/4-inch inputs, often combined into combo connectors so that you can plug mics, guitars, synths and the like into the same input. Many interfaces also offer a phantom power option, which is required if you want to use certain microphones.
Some audio interfaces also have MIDI I/O on them, which could save you from having to buy a separate interface for external MIDI gear. If you only intend to use a MIDI keyboard, though, remember that this could plug into one of your computer's other USB ports, so MIDI I/O might not be an essential requirement.