Have a product or business you are trying to make a profit off of? If you have a business, then you need some publicity for it to succeed. If you want to advertise yourself, then sure, you can do it online. However, another way is to set up a booth for a trade show.
At a trade show, you have the opportunity to show off your product or service to passing spectators. This is your chance to demonstrate the usefulness of what you are trying to sell. You can also pass out flyers and other promotional items. You can also get others to leave a number and email address so you can contact them. More info: trade show logistics