This is shorting article to let you know do not go to the Edit tab to look for Advanced Mode in SharePoint Designer 2013.
The simple article can save you minutes and even hours.
You might bump into a link like, SharePoint Designer: Its all about control (http://www.sharethepoint.com/sharepoint-designer-its-all-about-control/) So you see Edit File in Advance Mode, If you have used SharePoint Designer 2010 before, your guess is right. This is not SharePoint Designer 2013.
But if you get this link from the forums, https://social.msdn.microsoft.com/Forums/en-US/bb035480-45a0-41ba-bdef-2e7cd709ce77/how-to-enable-sharepoint-designer-2013-advanced-mode-which-is-alwayes-grayed-out?forum=sharepointdevelopment. Looks like the Advanced Mode is in Edit tab.
No, it is not. The correct place to find the Advanced Mode is in the Home tab in the latest SharePoint Designer 2013 with Service Pack 1 (could be the last version of SharePoint Designer).