How do I create hyperlinks in slack?

Paste a valid url I should think

http://this.is-a.url

Hmm, no support. Only full blown links, rather than a names hyperlink. sorry, should have been more precise.

Did you read?: https://get.slack.help/hc/en-us/articles/204399343-Sharing-links-in-Slack

Note: Hyperlinking words and terms in a Slack message isn't supported — to include a URL, paste it into the message input box. Visit Sharing links in Slack for more. 

Yes, this is one of the many reasons I prefer Gitter...

Hmm personally it seems like a bit of a security hole to to allow aliased links

At least you can see the url

Gitter shows you the link address when you hover over it… just like the web… which i should hope people do anyway...