Explain weak and strong entity sets?

Weak and Strong entity sets: A physically powerful entity set has a primary key. All tuples in the group are distinguishable through that key. A weak entity set has no primary key unless attributes of the tough entity set on which it depends are included. Tuples in a weak entity grouped are partition according to their relationship along with tuples within a strong entity set. Tuples inside each partition are discernible by a discriminator, that is a set of attributes. A strong entity set has a primary key. All tuples within the set are distinguishable through that key. A weak entity set has no primary key unless attributes of the strong entity set on that it depends are included. Tuples in a weak entity set are partitioned according to their relationship along with tuples in a strong entity set. Tuples within each partition are discernible through a discriminator that is a set of attributes.