Web Archive is a tool that allows users to view the history of websites in the browser. It can be used to find out what pages on your web site used to look like, from text content, to media content on a web page.
But it should be noted that not all pages and not all sites are saved, because Wayback Machine resources are limited - the service cannot save all sites and their versions daily. Priority is given to popular and frequently updated pages. Also, this problem can be encountered if site owners prohibit indexing and archiving with the robots.txt file or block access from various bots, including the web archive bot.
A web archive is like old notes in your phone where everyone wrote down different ideas. Sometimes some were implemented after several years and were useful. Or, were used to compare with current updates.
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