1) If you are editing a file (eg, html file) file and want to view it, the mapping \xf will do it. 2) If you want to execute the string under the cursor (): The mapping \x executes the "as is", whereas the mapping \xl executes it after pre-pending it with the full path to the current file. Example for \xf -- viewing an html file while editing it. Example for \x -- the string under the cursor can be a google search for the word mail on this web-site: (It can also be things such as the name of a file (foo.pdf, foo.bat) or directory etc.)