If you're writing a website link in a post or profile on Mastodon, it's important to include the https:// at the beginning as this makes the link clickable.
If you write the link without https:// then it just appears as normal text and people won't be able to click it open.
馃 NERDY BONUS TIP: Mastodon also supports several rare non-web types of link including gemini:// dat:// dweb:// gopher:// ipfs:// and ssb://. The "Gemini" link type is nothing to do with AI or Google.