A saving throw (sometimes called a save) represents an attempt to resist an effect being forced upon your character such as a spell, a trap, a poison, a disease, or similar threat. You don’t normally decide to make a saving throw; you make one because you’re at risk of harm. Although you typically will not want to, you can always choose to fail a saving throw.
To make a saving throw, roll a d20 and add the appropriate ability modifier. For example, you use your Constitution modifier for a Constitution saving throw.
A saving throw can be modified by a situational bonus or penalty, and can be affected by advantage and disadvantage, as determined by the Narrator.
Each class gives proficiency in at least two saving throws. The sorcerer , for example, is proficient in Constitution and Charisma saving throws. Proficiency in a saving throw lets you add your proficiency bonus to saving throws made using a particular ability score. Some monsters have saving throw proficiencies as well.
The Difficulty Class for a saving throw is determined by the effect that causes it. For example, the DC for a saving throw allowed by a spell is determined by the caster’s spellcasting ability and proficiency bonus.
The result of a successful or failed saving throw is also detailed in the effect that allows the save. Usually a successful save means that a creature suffers either no harm or reduced harm.