A more thorough explanation:

Subtenancy refers to a situation where a lessee (the original tenant) leases some or all of the leased property to a third party for a shorter term than their own lease. This is also known as a sublease.

For example, if John leases an apartment from a landlord for a year, but then decides to move out after six months, he may choose to sublease the apartment to his friend, Sarah, for the remaining six months. In this case, John becomes the sublessor and Sarah becomes the sublessee.

Another example could be a business owner who leases a commercial space for five years, but then decides to downsize the business after two years. They may choose to sublease a portion of the space to another business for the remaining three years.

Subtenancy can be a useful option for tenants who need to move out before their lease is up, but don't want to break the lease and risk losing their security deposit or facing legal consequences. It can also be a way for tenants to earn some extra income by subleasing a portion of their space.