Channeling

Channeling[a] is an enchantment applied to tridents that causes a lightning strike when thrown at an entity or lightning rod during a thunderstorm (in Java Edition) or at a lightning rod during any type of rain (in Bedrock Edition).

Channeling on enchanted books can be obtained from enchanting tables, drops from mobs spawned in a raid,‌[Bedrock Edition only] fishing, librarian villagers, and in the following structures' loot chests: desert pyramid, stronghold, ocean ruins, woodland mansion, pillager outpost, ancient city, mineshaft, dungeon, jungle pyramids, and from vaults in trial chambers.

Channeling summons a lightning bolt when an entity or lightning rod is hit by a thrown trident, if there is currently a thunderstorm occurring. This applies to most entities that the trident can collide with: mobs, players, armor stands, boats, minecarts, end crystals, item frames, paintings, leash knots, and even shulker bullets. It does not apply to ghast fireballs and wind charges, and to entities that the trident can't collide with (small fireballs, arrows, experience orbs, thrown item entities, primed TNT, falling blocks, wither projectiles, and so on).