Search Engine Marketing (SEM) is a digital marketing strategy used to increase the visibility of a website in search engine results pages. Coursera's SEM catalogue teaches you how to effectively optimize and advertise your website through search engines like Google, Bing, and Yahoo. You'll learn about keyword research, pay-per-click advertising, search engine algorithms, and the role of landing pages in digital marketing. Additionally, you'll understand how to measure and analyze the performance of your SEM campaigns, and how to continuously improve them for higher visibility and conversion rates. The skills learned will be invaluable for digital marketers, SEO specialists, or anyone looking to increase their website's visibility and traffic.