How do you add syntax highlighting for Less in Notepad++?

Download from this page the XML file of the language to add (such as Less)

In Notepad++ open Language menu > Define your language... and Import the file

To get LESS syntax highlighting, you have to download and import a user defined language file. Here are some links to language files:

• LESS language file, as listed in the Notepad++ User Defined Language List
• LESS language file on GitHub

Installation instructions from the GitHub repository:

• Download the less.xml file
• Open Notepad++
• Go to Language -> Define your language..., click on Import... and select the less.xml file you've downloaded
• Close and restart Notepad++
• Done

Another way to install language files is to copy them into a file in the Notepad++ installation directory.