One common misconception is the idea that noes and antinodes are the same as the crest and trough of a wave. They’re not. A node is a place on the wave that is permanently at rest. An antinode is where the wave is at its maximum (it will travel through a large up and a large down displacement).
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You’ll find standing waves when you look at columns of vibrating air or strings vibrating at resonance. This happens because of two things going on simultaneously:  when the wave hits the barrier, instead of continuing on, it gets reflected back.

The reflected wave constructively interferes with the next incoming waves, and the overall effect is that you have places on the string that never move and places where it’s always at a maximum. This effect is what we call a standing wave.

Nodes and antinodes aren’t really part of the wave because a standing wave really isn’t a wave at all… it’s just a visual effect that looks like a wave that doesn’t move. You have to perfectly time the interference of two (or more) opposite-traveling waves to get this effect.

Click here to go to next lesson on Simple harmonic motion.

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