Various features, including syntax highlighting, are dependent on the type of file that you're editing. For example
DOCTYPE is only special inside of HTML files, and closing a tag with
</ only makes sense in files that contain tags, such as HTML or XML.
If you just open Sublime and start typing, it assumes you're editing a plain text file until you tell it differently, which is visualized in the status bar in the bottom right, where you will see it say
In order to tell Sublime that what you're editing is HTML (for example) you need to do one of the following things:
- Save the file with an appropriate extension (e.g.
.html) so that Sublime knows what sort of file it is.
- Click where it says
Plain text in the status line, which opens a menu that allows you to select the appropriate syntax for the file that you're editing
View > Syntax from the main menu and pick the appropriate file type there (you get the same menu as mentioned in the previous step when you do this)
- Open the command palette (
Tools > Command Palette or the associated key which is visible next to the menu item) and enter
syn: to filter the command list to just commands for changing the syntax, then pick the appropriate syntax (you can type a partial name to filter further).