Tai-otoshi (体落), the body drop.

Nage-waza (throwing techniques), Te-waza (hand techniques), Gokyo 2nd set (Dai-nikyo).
Required for: 7th Kai (white belt with a brown stripe, JudoScotland); 8th Kai (white belt with a black stripe, JudoScotland); 9th Kai (red belt with a white stripe, JudoScotland); 4th Mon (yellow belt, British Judo Association); 8th Mon (orange belt, British Judo Association); 5th Kyu (yellow belt, JudoScotland); 4th Kyu (orange belt, JudoScotland); 1st Dan (black belt, British Judo Association); 2nd Dan (black belt, British Judo Association); 3rd Dan (black belt, British Judo Association); 4th Dan (black belt, British Judo Association); 5th Dan (black belt, British Judo Association).

About
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A hand throw: tori turns in, extends a leg across uke's shin, and drives uke over it with a strong rotation of the arms and trunk.

Step by step (standard right-handed form)
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1. From a right-handed grip, pull your partner's balance forward and to their right front corner, so their weight loads onto their right foot.
2. Step your left foot back and across behind you, turning your body side-on to them; you do not make back contact in this throw.
3. Extend your right leg across the front of their right shin, your foot planted just outside their ankle, knee bent, toes gripping the mat. The leg is a bar; it carries none of their weight.
4. Pull the sleeve hard past your left hip and drive the lapel hand across their chest, rotating your whole trunk to the left.
5. Their body rotates over the barred shin and they land on their back in front of you and to your left. Release the rotation only when the sleeve has guided them down.

Key points
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1. Your extended leg blocks the shin, carrying no weight
2. Throw with the hands and hips: it is not a leg lift
3. Bend the blocking knee, toes gripping the mat

Receiving it
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You are turned and drawn forward, and a straight leg appears as a bar across your shin while both hands wheel your shoulders on: your legs stop and your body does not. The fall is a clean forward rotation. Keep your chin tucked and swing your left arm ready; you land on your back past their leg, sleeve still held, left arm slapping.

Reference pages elsewhere
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Tai-otoshi on the IJF technique reference (International Judo Federation): https://judo.ijf.org/techniques/Tai-otoshi

From Waza Book: https://wazabook.com/techniques/tai-otoshi/