One of the best things about the web — its constantly evolving, easily modifiable nature — can also be one of its most frustrating faults. Because usually when a website modifies its content, any changes overwrite what came before it, sometimes without leaving a trace of the old content. Perpetually.com , a new site launching today at TechCrunch50 , is looking to solve this problem by offering companies a way to easily back up their sites. The company says that every year, 5-8% of 'bookmarked' content vanishes from the web as pages are modified and removed. Perpetually helps solve this problem by recording a history of every change on your site. And Perpetually doesn't just keep a copy of this content in an ugly search engine archive — you can actually view the content in context, as it originally appeared on the site. TechCrunch50 Conference 2009 : September 14-15, 2009, San Francisco