A more thorough explanation:

A contingent remainder is a type of future interest in real property that is uncertain in some way. It can come in two forms:

• A remainder in an unknown person
• A remainder that has a condition precedent to possession

For example, if a grantor conveys property "to A for life, then to B's children," the remainder in B's children is contingent because it is uncertain how many children B will have. Another example is if a grantor conveys property "to A for life, then to B if B graduates from college." The remainder in B is contingent because it is uncertain whether B will graduate from college.

Contingent remainders are non-vested, which means that they are not yet capable of being possessed. They are also subject to the Rules Against Perpetuities, which limit how long a future interest can last. Contingent remainders become possessory only if certain conditions are met, such as the natural termination of a prior estate or the fulfillment of a condition precedent.

If a contingent remainder has a condition precedent to possession, it must transfer immediately, with no gap of time, upon the natural termination of a prior estate once the condition precedent is met. An alternative contingent remainder exists when the grant lists two possible takers depending on whether a condition is met.

Overall, contingent remainders are future interests that are uncertain in some way and can only become possessory under certain conditions.