Postage is the fee you pay to send mail through the postal system. When you mail a letter or package, you buy postage by putting stamps on it or paying at the post office, and that payment covers the cost of transporting your mail to its destination.

The amount of postage depends on what you're sending. A regular letter to someone across town needs only one stamp, but a heavy package going overseas requires much more postage. If you don't put enough postage on your mail, it gets returned to you, or sometimes the person receiving it has to pay the missing amount.

Before stamps were invented in 1840, people usually paid postage when they received mail, not when they sent it. This created problems because recipients often refused to accept letters they didn't want to pay for. The invention of the postage stamp, which you buy and stick on mail before sending it, revolutionized communication by making it simple and reliable.

Today, buying postage is how you access a remarkable service: for the price of a stamp, you can send a letter anywhere in the country, and it will arrive in just a few days.