Should you buy Active or Passive speakers?
There are big differences between Active and Passive speakers, but it's quite easy to choose which will be best for you.
Active (or powered) speakers have an amplifier built into them so you don't need a separate power amplifier. This makes them more versatile in that you can use one speaker on its own, or easily daisy chain more speakers or subs on without worrying about anything. They're simple to use, and great for bands playing in different sized venues for example. Because they contain their own power amp, active speakers will often have RCA line inputs on the back (for a music source) and XLR or jack microphone inputs so you can use them without the need for a mixer for meetings, for example (see right). If you need more inputs you'll need to connect them to a Passive Mixer.
Active speakers need to be plugged into the mains.
Because they have controls on the back they're not suited for wall-mounting.
Some active speakers are bi-amped, meaning they can power a passive speaker as well as themselves, very useful for stage monitors as only the active needs to be connected to the mains.
Passive (or non-powered) speakers need to be powered by a separate power amplifier or a powered mixer. The power rating of the amplifier or powered mixer is matched to the speakers so they can only ever be used as a complete system.
They don't have any inputs on the back for microphones or devices, so need to be connected to a mixer or mixer/amp or a bi-amped active speaker.
Because there's nothing on the back to access and they don't need a mains power supply they're ideal for wall-mounting.