Translations:Wiki/Help:Contents/50/en
From LimeSurvey Manual
Every action made by every person on a wiki (like creating and editing pages) is logged - along with the information of who done it and when - and can be reverted back at any time. So, if you spent the whole week working on a page and then you came home drunk on Saturday and erased all the content of that page, don't worry because the 
button will always be there for you.