Slow, glowing chords.
A pad is the sound that fills the space behind everything else: it fades in, holds, then fades away. Play three or four notes together and hold them rather than picking out a tune.
Slow, glowing chords that fill a room.
No MIDI keyboard? Play with your computer keys: bottom rows are the lower octave, top rows the higher one. Hold Shift to sustain. ← → octave, ↑ ↓ semitone.
Online synth pad
A pad is the sound that fills the space behind everything else: it fades in, holds, then fades away. Play three or four notes together and hold them rather than picking out a tune.
Connect a MIDI keyboard and the mod wheel opens the filter, so you can swell the sound with your left hand while your right holds the chord. The online synthesizer page exposes the same controls if you want to see how it is built.
Synthesized rather than recorded, so it starts instantly. Free, no account, and nothing you play is sent anywhere.