You can install user scripts written in JavaScript to add helpful features to your account, and to automate various tasks. You could write your own scripts. But many user scripts have already been written by Wikipedians, and they are ready to be made use of. To enable these scripts, simply copy and paste them into your common.js file. (Only logged-in users can install scripts). This will allow use of the script in any Wikipedia skin (Vector is the default skin).

Examples of scripts:

• wiktLookup – Double-click a word, and go to its definition on Wiktionary.
• Watchlist sorter – Sorts your Watchlist by namespace, and shows the pages for each namespace in alphabetical order. Also adds spacing for further ease of reading.

Some of the most popular scripts have become Gadgets, which can be enabled simply by checking an option under the gadget tab of your user preferences.