An advertising agency is like an expert in helping businesses get the word out about their products or services. Ad agencies can make ads that can be seen or heard on TV, radio, newspapers, magazines, and online. They help make sure that the right people see the ads and understand what the business wants them to know. For example, if a store wants more people to learn about a sale they are having, an ad agency will create an ad (like a commercial on TV) to make sure people know about the sale. Sometimes ad agencies also make ads for campaigns that help spread important messages, like staying healthy or helping the environment.