In order to make your website available to everyone on the internet it has to be put on a computer that is 24/7 online with the internet. Those are usually large and powerfull computers placed in air conditioned rooms and maintained by a team of professionals.
This kind of service is called hosting, and We offer our clients very salable and quality hosting. All websites are hosted on Dreamhost servers with 99% of work time (uptime). Uptime marks percentage of time that server is online (usually calcualted for one year period).