Website defacement is an attack on a website that changes the visual appearance of a website or a web page. These are typically the work of defacers, who break into a web server and replace the hosted website with one of their own.
Defacement is generally meant as a kind of electronic graffiti and, like other forms of vandalism, is used to spread messages by politically motivated "cyber protesters" or hacktivists. Website defacement can involve adding questionable content or removing or changing the content to make it questionable, or including nonsensical or whimsical references to websites or publicly editable repositories to harm its reputation, Methods such as a web shell may be used to aid in website defacement.