I'm a Londoner who always rides the Tube. Here are 10 features of the Underground that would surprise most Americans.

The author travels on the London Underground — or Tube — several times a day. Roya Shahidi Known as the Tube, the London Underground is an essential part of everyday life for most Londoners. Some of its characteristics are uncommon in American subway systems and can be confusing. From unwritten etiquette rules to fare must-knows, here are some surprising things about the Tube. While it's ridiculously busy at rush hour and way too hot in the summer, the Tube is an essential part of life in London. As a local, I sometimes use the public transit system — formally called the London Underground —more than four or five times on some days, as it's often the quickest way to get around the city. I can thank the London Tube for saving me from missed flights or arriving late for an interview.