Secure your domain name for longer
A Top Level Domain (eg. .com, .net, .org, .biz, .info) can be registered from 1 to 10 years. If you're registering a domain name for an established business or a name that's personal to you (eg. your surname) then longer registration make more sense.
Why register for multiple years?
There is no reason why you can't renew your name every year, maybe you only need the domain temporarily or you are speculatively registering a domain name for a new idea. In this situation the ability to register a domain for only 1 year has sound reason. There are however some good reasons why registering your domain for longer makes good business sense.
Protecting Your Identity
Your domain name is your online identity, whether it's the name of your business or your own name, loosing your domain can have serious repercussions. Yearly registrations exposes you to increased opportunities to lose your domain eg. you change your eMail address and renewal notices don't reach you. Once your domain expires your web site and eMail stop working, affecting your business.
If your domain expires and goes into redemption you will have to pay more to redeem and renew it. In the worst case scenario you miss the redemption period and someone else registers your domain which will result in you having to pay for re-branding of all your marketing materials including you site. Worst of all, you'll have to establish a new eMail address and let all your customers know.
Registering your domain for longer periods reduces the risk of this happening to you.
By registering your domain name for the maximum term you pay today's price and are you're protected from any price increase until your next renewal. There is a chance that the registries running the different domain extensions will raise their prices in the future (10 years is a long time for them to keep their prices fixed).
The other price incentive for registering your domain name for a longer period is a lower equivalent yearly cost:
Equivalent yearly cost
NB. The prices stated are for guidance only and may not reflect current charges.
Search Engine Ranking
There is general consensus that the top search engines like Google are using registration length as one of the many factors to calculate rankings. The consensus is based on the theory that a person who renews their domain name for 10 years is more likely to build a web site of greater worth than someone who only holds their domain for 1 year. This is further supported when you consider those who participate in spamming or domain tasting normally only register domains for 1 year.