The slingshot is a semi-utility weapon that's meant to fill out Minecraft's ranged combat game. It's not as long-range as a bow or as powerful as a crossbow, but it presents a much wider array of ammunition you can fire to inflict effects and more specific enchants that complement the playstyle it creates.

Each type of ammunition takes a different amount of time to load into the slingshot and deal different amounts of damage, so keep that in mind when using this in combat.

The ammunition list is quite expansive:

Utility items:

Both regular and redstone torches can be fired from the slingshot, and will place themselves if they land on a valid spot (otherwise they’ll just break). Regular torches have a chance to light mobs on fire.
All types of seeds can be loaded and fired, though not very far. They’ll plant themselves upon hitting farmland, or break upon hitting anything else.
Potatoes and carrots work the same way, except they deal more damage.
Ender pearls can be flung VERY far, farther than a player could launch them.
Saplings work the same way as the other farmables, planting themselves if they hit dirt or grass. They also have the bonus of dealing more damage than potatoes or carrots.

Defensive items:

Sand will burst into a blinding cloud on impact. Red sand will do the same.
Glowstone dust will create an area effect cloud that makes mobs glow, briefly.
Redstone dust will stun everything caught in the cloud it makes.
Wheat will create a cloud of chaff that also inflicts blindness, but can be lit on fire for extra fun!

Offensive items:

Blaze powder bursts into clouds of flame, dealing high damage to those caught in it.
Gravel makes sprays of pellets, useful for good crowd control.
Soul sand works almost identically to regular sand, with a slower load time and a shorter range, but has a chance to inflict wither in addition to inflicting blindness.
Golden carrots fly quite far and hit hard, due to the fact that they’re coated in gold.
Gunpowder can be shot at a mob to coat them with it. Lighting them on fire afterward will cause them to explode!
TNT can be loaded into the slingshot. Hold a flint and steel in your offhand and right click to light the TNT, right click again to fire. Need I say more?

There are three enchants that are obtainable for the slingshot.

Capacity goes up to V, and each level effectively increases the magazine size of the slingshot by 1, but adds more reload time. Capacity I-III can be obtained through regular enchanting. Capacity IV can be bought from expert librarian villagers for 6 emeralds. Capacity V is a treasure enchant and can only be found through fishing or looting.

Ignition automatically lights TNT and wheat when they're fired, saving you some trouble. It's obtained with regular enchanting. Gunpowder becomes a utility item with an Ignition slingshot, creating a small blast that can be used to blast-jump up to higher ledges (with a good run up) or push mobs away.

Reload goes up to VI, and each successive level decreases the reload time of a slingshot by a set percentage. Reload I-III can be obtained through regular enchanting and reduce reload time by 5, 10 and 20%, respectively. Reload IV and V can be bought from a master librarian villager for 8 and 10 emeralds each and apply 35 and 40% reductions. Reload VI is a treasure enchant that cuts reload time neatly in half but can only be found via looting or fishing.

In short, the slingshot is a blast-jumping, remote-planting, mob-stunning, TNT-flinging tool/weapon hybrid for the unorthodox Minecraft explorer.

Crafting recipe, just to make it a bit easier

Slingshot