Contextual advertising is a type of online advertising that helps businesses show ads to people who are interested in their products or services. It works by looking at the words in a person's search or website and then showing ads related to those words. For example, if someone searches for a new phone, they might see ads for different phone stores or phone plans. Contextual advertising helps businesses make sure that they're showing their ads to the right people—people who are more likely to be interested in what they have to offer.