SEM or SEO agencies

The job of SEM or SEO agencies is to improve your client's organic search results on search engines like Google. This usually involves improving the unpaid traffic that comes from the search results and includes both direct and paid traffic (SEA = Search Engine Advertising). Search Engine Optimization (SEO) is the process of improving a website's visibility on search engines like Google.
SEM stands for search engine marketing and includes SEA and SEO.