Synthesizers

A synthesizer is an electronic instrument, often controlled by a piano style keyboard. A synth's sound is generated from an oscillator or waveform which is passed through different controllable stages. These could be filters, LFOs (used to make rhythmic changes to specified sections of the signal path), amp envelopes (which give you control over how the sound fades in, fades out and sustains) and effects (delays, chorus, reverb etc.). Synths are very versatile instruments and just one synthesizer can give you a phenomenal amount of sound creation mileage.

There's no correct answer to this question. Some people love the warm tones of analog, while others feel limited by the polyphony analog usually offers. Digital usually grants a wider palette of sounds and can even recreate the sound of analog fairly accurately. If you're really stuck over which to go for, Roland's JDXa synthesizer actually offers both analog and digital synthesis. The sounds can either be kept separate or blended together to create new and unique tones.