In D&D 5e, concentration can be broken in several ways. Here are the most common ways to break concentration:

• Taking damage: Whenever you take damage while concentrating on a spell, you must make a Constitution saving throw to maintain concentration. The DC for this saving throw is equal to 10 or half the damage you took (rounded down), whichever is higher.

• Casting another concentration spell: If you start casting a new concentration spell, the current spell you’re concentrating on immediately ends.

• Using a concentration feature: Some subclasses have features that read “as if you were concentrating on a spell” — using one of these immediately ends concentration on a spell or other such feature.

• Being incapacitated or killed: If you become incapacitated or die, you automatically lose concentration on any spells you were maintaining. Becoming paralyzed, stunned, unconscious, or petrified also causes you to become incapacitated, thus ending your concentration.

• Environmental effects: The DM can rule that certain environmental effects require a concentration check. For example, a wave crashing over you while you’re on a storm-tossed ship could require a DC 10 concentration check.

Its important to note that casting a spell that doesnt require concentration or taking normal actions like moving and attacking dont break concentration.