Website maintenance is an activity designed to keep a website running smoothly. It may be done on a regular basis, or scheduled as needed. In some cases, access to the website may be temporarily restricted while maintenance is performed, in which case a notice may be sent to users ahead of time to make them aware of the fact that the site will not be available during a specific time period on a particular day. One reason to perform maintenance is to update the website. It is important to keep information up to date and to make sure that the systems used to run the site are also current. Having the latest programs on the backend will keep the website more secure, in addition to allowing people to keep up with changes. It will also improve user experience on the site, which can be very valuable for those that want to build and retain large user bases. If a site is going to be disabled while it is worked on, it may be put into maintenance mode. During this time, a notice appears on the site explaining that it is temporarily unavailable, ideally with a note stating when the site should be back. During maintenance mode, major maintenance tasks can be performed without having to worry about keeping the site functional for users at the same time. This can include everything from changing a content management system to installing new tools on the site.