Attack Roll | Game Master Companion 5e

Attack Roll

When you make a melee or ranged attack, your attack roll determines whether you hit or miss. Some spells require the caster to make an attack roll to determine whether the spell effect hits the intended target. (94)

You hit if: your attack roll ≥ target’s AC.

If you hit, then roll for damage.

Melee or ranged attack roll

1d20 + attacker's ability modifier + attacker's proficiency bonus (if attacker is proficient with the weapon used) + any other modifier.

Spell attack roll

1d20 + spellcaster's spellcasting ability modifier + spellcaster's proficiency bonus.

Why advantage or disadvantage could apply.

Rolling 1 or 20.