You have probably seen other websites where you can search for content or images by typing a part of it. If you want to find a list of all the cards in the entire game, you have to type every card in the game. This would be a really long and tedious process.

How does Reddit HearthSearch work?

When you type a card name in the text field, a search box will appear. This is where you can type part of the card name to find cards matching that portion of the name. You can see the results in the drop-down list below. You can also see the card image and other related information in the form of text.