A more thorough explanation:

In property law, a future interest is the right to possess property in the future. It is different from a present right to property, which is also known as a possessory estate. A future interest can be conditional or unconditional and is created when a defeasible estate is formed. It will either take effect after the natural termination of the prior estate or cut short the prior estate.

• Life Estate: A life estate is a future interest that will result in ownership of the property only after the present possessory estate has run its course. For example, if a person grants a life estate to their spouse, the spouse will have the right to live in the property until they die. After their death, the property will pass to another person.
• Executory Interest: An executory interest is a future interest in property that will be triggered on the happening of a stated event and will pass the property to a third party. For example, if a person grants a property to their child, but only if the child graduates from college, the child will have an executory interest in the property. If they graduate from college, they will become the owner of the property.
• Right of Entry: If the condition is violated, the grantor has the voluntary right to reclaim the estate. For example, if a person grants a property to their friend, but only if the friend does not sell the property, the person will have a right of entry. If the friend sells the property, the person can reclaim it.
• Possibility of Reverter: If the condition is violated, the estate is automatically restored to the grantor. For example, if a person grants a property to a school, but only if the school uses the property for educational purposes, the person will have a possibility of reverter. If the school stops using the property for educational purposes, the person will become the owner of the property again.

These examples illustrate how future interests work in property law. They show that a future interest can be created for various reasons and can be conditional or unconditional. They also show that a future interest can be triggered by a specific event or condition and can pass the property to a third party or return it to the grantor.