"I just wanted to let you know that Ben has been so great with us. I know we were picky (to say the least) before/after our new site went live, but Ben was responsive the whole time. He continues to help us out with website stuff and we really appreciate everything he has done! Also, Chris has been wonderful with SEO stuff as well. He has been very helpful with the SEO project and helping me not let things fall through the cracks. You have a great team and we have enjoyed working with them!"
Keyword research tells you what topics people care about and, assuming you use the right SEO tool, how popular those topics actually are among your audience. The operative term here is topics -- by researching keywords that are getting a high volume of searches per month, you can identify and sort your content into topics that you want to create content on. Then, you can use these topics to dictate which keywords you look for and target.
While SEO allows you to optimize your website for a greater chance in appearing higher in search results, and online advertising allows you to send promotional content to the target audience of your choosing, SEM combines both benefits as your content is both optimized for higher search rankings and is placed primarily in front of audiences who are most likely to convert when they click on your ads.