h Removal (h抜き, Etchi Nuki) is an internet etiquette rule of removing the 'h' from 'http://' or 'https://' to avoid how websites automatically convert detected URLs into direct links, which may be discouraged in some parts of the internet for a wide variety of reasons.

The theory behind dropping the 'h' is that search engines won't crawl the target website if there's no direct link, and website owners are denied the ability to see what webpage you came from.¹⁾ On top of that, it's also a workaround for communities that deny posting links to ward off spam bots.²⁾ In a way, it's kinda like how people don't blatantly post their email address in order to avoid being put on spam mailing lists.

However, a downside is that it could be 'inconvenient' for some users, though most modern web browsers will be able to recognize links with the first 'h' removed as a 'typo' and bring you to the right page. It's also sorta meaningless if browser and website developers allow links with the first 'h' removed to be recognized anyways, so you have to use alternatives like changing the 't' in 'http://' or 'https://' to 'x' instead.

• It's believe that this started on 2channel, but the reason is unknown. Some say that users didn't want unauthorized porn websites with copyrighted content to get sued by copyright holders, while others say they were annoyed by the “jump.2ch.net” page or didn't want the website to gain ad revenue.

• h Removal on Niconico Encyclopedia
• h Removal on Japanese Wikipedia