Source: Player's Handbook

Evocation Cantrip (Sorcerer, Wizard)

Casting Time: Action
Range: Touch
Components: V, S
Duration: Instantaneous

Lightning springs from you to a creature that you try to touch. Make a melee spell attack against the target. On a hit, the target takes 1d8 Lightning damage, and it can’t make Opportunity Attacks until the start of its next turn.

Cantrip Upgrade. The damage increases by 1d8 when you reach levels 5 (2d8), 11 (3d8), and 17 (4d8).