Some spells require concentration to keep their magic active. If concentration ends, the spell ends.
You can concentrate on only one spell at a time. Casting another concentration spell ends the previous one.
Taking damage while concentrating forces a Constitution saving throw. The DC is 10 or half the damage taken, whichever is higher.
If you take damage from multiple sources, make a separate saving throw for each source.
Concentration ends if you are incapacitated, die, or choose to end it at any time with no action required.
The DM can call for a DC 10 Constitution saving throw to maintain concentration during severe environmental interference.