An algorithm is a set of instructions designed to perform a specific task. This can be a simple process, such as multiplying two numbers, or a complex operation, such as telling you which route to the airport will be the fastest. Algorithms matter because they control how search engines evaluate your website. The more features that your site has that the algorithm is looking for, the more relevant it thinks you are and the higher it will display your site when someone searches for what you are selling.
For example, right now, the Google algorithm is placing a high value on using Header Tags (h1, h2, h3, h4, etc.). If you know that Google wants header tags and you don’t have any, that’s a pretty easy thing to add to your site to increase your favor with the Google search engine gods. All those little details add up, and they are absolutely worth taking the time to do.