Search Engine Marketing (SEM)
Concepts used in search engine marketing are very close to SEO with a few significant difference regarding cost and responsiveness to action.
Keywords, Ads & Landing Pages
A journey of a user begins with entering a search phrase tirggering your ad, followed by the visit of your site/landing page and hopefully converting. Building a SEM campaign though, usually happens on reverse. We start building a landing page, create ads related to the landing page and then add keywords to a campaign within which may trigger the ad.
A few years ago, Google Ads (named Adwords then) promoted the setup of brand search campaigns. Setting up brand name as keyword pointing to the homepage. Unfortunately, nowadays it is mandatory for any established business to maintain such a campaign.
The Importance of Tracking
Spoiler Alert: Extremly important! :) Optimizing a campaign may require many cycles of launching campaigns, reporting and improving.
It should be possible to attribute all events (clicks, submits, conversions) on landing pages or website to source and medium having referred the user.
An error while setting up ad campaigns may cost thousands of dollars without the option to roll back. SEM providers have no interest to provide safety features from errors to happen.