This legal expression has nothing to do with renting property. When you buy
a property with a partner you have a choice of ownership. As Tenants in Common
you own a pre-agreed share of the property (usually 50% of course). On your death
this share can be willed separately and need not necessarily be left to your partner.
The alternative, Joint Tenants (q.v.), is the
more common and means you share all of the property equally and so, on death,
the survivor automatically inherits the whole property.