The Linkify button will create, with one click, a link from anything in the post that looks like a URL. You can also specity the displayed text like this: www.example.com|click_here The underscore is replaced by a space: click here
I added another way of creating links with multi-word text, allowing spaces and avoiding the need for underscores: www.example.com{{This site is an example.}} which generates: This site is an example.
That's easier for longer texts, for example a title copied from the target website.