10 Key SEO Terms Designers Need to Know:

Keyword: A word or phrase users type into search engines. You want to add lucrative keywords to your webpage content because it will make your site easier to discover via search engines.
Keyword Density: The percentage of how often the keyword is used on a web page. If the keyword density is high, then it will affect your Pagerank negatively.
KCI: KCI is short for Keyword Competitive Index. This measures the average monthly searches for a keyword compared to the demand (competition) for the keyword. Ideally, you want a keyword with high search volume and with a low competition factor.
Link Building: Getting external sites to link to your webpage. This increases trust, which in turn increases your Pagerank.
Pagerank: Google determines a link’s trust and popularity by assigning a number between 0 and 1. Learn more about how to rank in Google with this in-depth course, Master SEO Rankings.
Meta Description: The description about your website that shows on the search engine results page.
301 Redirect: A permanent server redirect. This is great for removing duplicated content.
Index: As a noun, it means the database of web pages and their content. As a verb, it means to add a web page to a search engine index.
Alt Text: Is a description that’s added to a graphic. This helps with discoverability as the image will show up in image search results.
Bot (robot, spider, crawler): A program that scans a webpage’s content. This is how search engines determine where to list web pages on search results, and how search engines find penalty-worthy SEO errors that affect Pagerank.

Source: howdesign