All too often, people dramatically overthink the most basic keyword research concepts; keyword generation should start simply with answering the question of "What products or services do you sell?" If you sell dog food online, the root words dog and food alone would be very poor keywords because on their own, neither dog nor food do a remotely good job at describing what you sell. Though this example makes it obvious, many times we have to fight through our urge to include those bigger, broader root keywords.
Ranking refers to the process search engines use to determine where a particular piece of content should appear on a SERP. Search visibility refers to how prominently a piece of content is displayed in search engine results. Highly visible content (usually the content that ranks highest) may appear right at the top of organic search results or even in a featured snippet, while less-visible content may not appear until searchers click to page two and beyond
So if you think about it, SEO is really just a process of proving to search engines that you are the best site, the most authoritative, the most trusted, the most unique and interesting site that they can offer to their customer - the searcher. Get people to talk about you, produce good quality content, get people to link to you, and Google will be more confident that you are the best result that they can offer to their searchers, and that’s when you will start ranking on the first page of Google.
Most businesses are aware that the search engines can drive massive traffic to their web properties. Not just any traffic, but traffic that actually converts into leads and sales. Even though there are other ways to gain online exposure, Google still leads the pack when it comes to helping you get the best bang for your marketing buck. This is mainly due to its huge user base and market share.
Search engine marketing (SEM) is a form of Internet marketing that involves the promotion of websites by increasing their visibility in search engine results pages (SERPs) primarily through paid advertising. SEM may incorporate search engine optimization (SEO), which adjusts or rewrites website content and site architecture to achieve a higher ranking in search engine results pages to enhance pay per click (PPC) listings.
In theory Google doesn't take note of descriptions. [And yet Google highlights keywords in descriptions.] But the greatest effect of a good description is click through rate, which is a ranking factor. So if your description is a good call to action and people click on it then Google will notice and (assuming people don't bounce from the site because the content is no good) your ranking should increase.
Thanks for the helpful information discussing the differences and similarities between SEO and SEM. The information was enlightening because a search engine optimization company like the one that I own is relatively new at starting. We believe everyone should always check out their sources because every different perspective is very different so all approaches can be understood differently.