SEM (Search Engine Marketing)
SEM is the umbrella term for getting visibility on search engines through paid placement, primarily the ads you see above and beside organic results on Google and Bing. In its strictest sense SEM means paid search specifically, though some people stretch it to cover all search marketing, paid and organic combined.
The appeal for a founder is speed and intent. Unlike SEO, which compounds slowly, SEM buys you the top of the results page today for the exact terms your buyers are typing, and those buyers are often ready to act. You bid on keywords, pay per click, and can switch spend on or off instantly, which makes it ideal for testing demand and capturing high-intent traffic. The catch is that it stops the moment you stop paying, and costs rise as competitors bid against you, so it works best as demand capture alongside organic channels that build over time.