I'm new into Wordpress Wordpress plugin development. I wish to create a wordpress plugin which adds the ability to make use of any custom code within editor to render it into another thing. For example should i be mentioning my Hacker News profie and i'm while using code H(HackerNewsID) then after posting it can make a Link to Hacker News pointing to my profile.

What feature of Wordpress might be best fit for this?

Thanks