A call to action is usually a button or activity that makes it clear to your audience what you want them to do. A few examples: "Contact", "Place an Order", "Schedule", etc.

The site should load and function correctly in Internet Explorer/Edge, Chrome, Safari, and Firefox.

Form encryption, especially on checkout pages, is important to prevent information from being intercepted. This could include login credentials, email addresses for newsletters, and credit card information for purchases.

A privacy policy is usually located as a link at the bottom of the page and clearly explains how a user's information will be used by the site owner.

An ALT tag is alternative text that helps a screen reader or search engine crawler understand what the image is and its purpose. This information is considered "metadata" that isn't obvious to the user, but can be added on the back end of the website and communicates important information to search engines. 

Is your site built primarily in HTML? Is the CSS optimized, or are there a lot of CSS exceptions? Is PHP used correctly? It's ok to say IDK!

Keywords are used to communicate primary content to search engines. A keyword or keyphrase is what a user might type into a search engine to find the site.

A sitemap provides a search engine with a map of your site's structure. Usually this is created by a plugin or program in the backend of your site.