Everything you write on Wikipedia must be attributable to a reliable source.

Wikipedians are working to create an accurate encyclopedia. Adding sources means other editors and readers can fact-check the claims.

Editors (yourself included) can challenge unreferenced statements by adding a {{fact}} tag in Wikicode, which adds a [citation needed] tag to the statement. Remember, editors may remove unreferenced material on sight, so adding a citation helps prevent your work from being deleted.