Wikipedia:Suppress display of the fundraising banner
The Wikimedia Foundation's annual fundraiser includes banner ads that some find annoying. The fundraising banner can be suppressed by logged-in editors (if you do not have an account, you may create one here). Once you are logged in, simply go to Special:Preferences, click on the Gadgets tab (far right) and check the option under the "Browsing" heading which reads "Suppress display of fundraiser banners". Click "save" at the bottom of the page and refresh your browser.
Users without editor accounts can use ad blockers built into browser to achieve the same goal. A web search for "block Wikipedia donation banner" or similar search terms will deliver up-to-date results.