Covenant of Quiet Enjoyment
Covenant of quiet enjoyment is a landlord's promise that neither the landlord, his agents, nor people with superior title will interfere with the tenant's exclusive possession of the land.
If one of these people physically removes the tenant, it is an actual eviction.
It is breached if the landlord, his agent, or a paramount title holder actively interferes with the tenant's possession or if the landlord's inaction if the face of a legal duty to act results in interference.
If this interference is sufficiently serious so as to deprive the tenant of the benefit of his possession and he departs promptly as a consequence, the departure will escalate the breach into a constructive eviction.
A breach of the covenant of quiet enjoyment can be through omission or commission.