All three end a contract, but not the same way
In everyday conversation these words often get used interchangeably, but in many legal systems they are distinguished by when the contract's end takes effect (going forward only, or retroactively as if it never existed) and by what caused the ending (a breach, versus a problem with how the agreement was formed). Terminology and exact rules vary a great deal by country, so treat this as a general conceptual map rather than a specific legal rule.
Termination: ends the relationship going forward only
Termination typically applies to ongoing contracts — a lease, an employment agreement, a subscription — and cuts off the relationship from that point on, while whatever was already performed stays valid. If a six-month lease is terminated after three months, the first three months of tenancy and rent payments remain valid; only the remainder of the relationship ends.
Rescission: unwinds the contract as if it never happened
Rescission typically applies to one-time transactions, like a sale, and is often triggered by the other party's failure to perform their obligations. Unlike termination, it generally unwinds the deal retroactively, including whatever has already been exchanged — for example, if a seller never delivers the goods, the buyer may be able to rescind the sale entirely rather than merely ending it going forward.
Cancellation (avoidance): for a defect in how consent was given
Cancellation or avoidance, in many legal systems, is not about the other party breaking the deal — it addresses a problem in how the agreement itself was formed, such as one party lacking legal capacity (a minor without a guardian's consent), being deceived (fraud), being coerced (duress), or acting under a significant mistake. Like rescission, it generally undoes the contract retroactively.
Restitution generally applies to rescission and cancellation, not termination
Where a contract is rescinded or cancelled, the parties typically must return whatever they already exchanged to restore the original position. Termination, by contrast, usually does not carry this duty for the period before the end date, since things like use of a rental property or work already performed generally cannot be physically given back.
Ending a contract does not erase a damages claim
In most legal systems, ending a contract through termination or rescission doesn't by itself eliminate a separate claim for damages caused by the other party's breach — the two issues are typically handled independently.
Everyday examples for each concept
Cancelling a gym membership partway through its term is generally a "termination" of an ongoing agreement. Unwinding the purchase of a seriously defective appliance is closer to a "rescission." A minor entering into a purchase contract without a guardian's consent, which the guardian later undoes, is a common textbook example of "cancellation/avoidance."
Things worth checking before you sign
When reviewing a contract, it helps to confirm the specific conditions that allow ending it, how much advance notice is required, and how any early-termination fee or settlement is calculated. For a dispute involving real money or a complex agreement, consult a lawyer rather than relying on general information like this.