XSS - Where the name is from?

Cross-site scripting (XSS) vulnerabilities occur in the following scenario:

• From a web request not trusted data enters a web application (blog, whatever…)
• The web application dynamically generates a web page that contains this not trusted data.
• The application does not prevent the data from containing the content that is executable by a web browser, such as JavaScript, HTML tags, HTML attributes, mouse events, Flash, ActiveX, etc.
• Browsers access the the generated web page and execute malicious code.
• Since the script comes from a web page that was sent by the web server, the victim’s web browser executes the malicious script in the context of the web server’s domain.
• This violates the web browser’s same-origin policy, which states that scripts in one domain should not be able to access resources or run code in a different domain and there for the name XSS