The sooner you search for the name you want, the better your chance of registering it before someone else. You also might want to check out the domains pre-order program today.
You can register a domain name for a period of 1-10 years, after which the registration expires. You will be notified and given the right to renew the domain name for an additional period before this happens.
To extend your domain’s registration period, you must pay a renewal fee. If you choose not to renew the domain, it eventually becomes available to be registered by the public again.