Hi,
Most of web host give 99.9% Uptime Guarantee. what is Web Hosting Uptime ?

Hosting uptime means the extent of time the server remains in running position. If you want to enjoy the best services of the host or want your site on the server for most of the time, then ask for higher uptime from your host. Uptime is important not only for web providers but also to the owner of the site, it is because if there is more downtime then it creates problem to the user of the site, and then to site owner as he faces loss of money and then to the reputation of the web host as he already took guarantee for giving higher uptime. And this happens because all the three are inter linked with each other. Web host offer 99.9% uptime that means there will not be down time less than 2 minutes a day.