What is a common feature of roller coasters that provide extreme thrills?

Vertical loops are a defining characteristic of roller coasters designed to deliver extreme thrills. These loops challenge riders by taking them upside down, which creates an intense sensation of weightlessness and g-forces that can be exhilarating. When incorporated into a roller coaster's design, vertical loops can significantly enhance the overall experience, as they not only provide a thrilling moment but also test the riders' ability to handle the unusual orientation and forces at play.

Other elements like high speeds, twists and turns, and drop towers also contribute to the thrill factor in roller coasters. High speeds enhance the intensity of the ride and increase the adrenaline rush. Twists and turns add excitement by changing direction rapidly, which can be exhilarating. Drop towers, while they do provide a thrilling free-fall experience, are a different type of attraction and are not typically part of traditional roller coasters. However, vertical loops stand out specifically for their unique ability to turn riders upside down while stationed on tracks, making them iconic in the realm of roller coasters that prioritize extreme thrills.