To add links to your Tumblr bio, you'll need to use a simple HTML code. Tumblr doesn't give you any sort of built-in way to add links yourself, so you'll have to copy and paste the code in manually.

Adding a Subscription Link to Your YouTube Channel. The more subscribers you have on your YouTube channel, the more views your videos get.

In order to add source code to your page, you'll have to have some code to work with. Whether it's an application that links to your newsletter or some other feature, track down the HTML, CSS or ...

Discover fundamental HTML rules every beginner should master. Leveraging our expert suggestions, start building your web pages today. ... The HTML code for adding links is: ...

Search Engine Land's Guide to SEO Chapter 3: HTML Code & Search Engine Ranking Success Factors explains HTML elements & using structured data.