As the one essential piece of equipment in the sport, running shoes sit at the center of many fierce debates. What sort of technology should be allowed? Do maximalist or minimalist shoes reduce injury? How many pairs do you need and how often should you replace them? Do you even need shoes at all?

The massive quantity of running shoes on the market makes choosing the right pair a daunting task. It’s even more confusing when you consider that even though they are all designed for the same sport, they look, feel and are priced very differently.

But when you look beyond the labels and features, a running shoe is just that: a shoe you run in. Any pair can be your running shoes, technically, regardless of how the manufacturer markets them. How you feel when in them matters more than what they’re designed for. Of course, you’re more likely to feel comfortable running in a sport-specific shoe that caters to your needs, for a variety of reasons.

What Makes a Shoe a ‘Running Shoe’?

Early models of running shoes look more like formal footwear than sports equipment. From the late 1800s through the early 1900s, shoemakers constructed runners with leather uppers and heeled, stiff soles—often with spikes attached.

Fast forward to the 1970s, when running started to gain popularity. Companies used materials like rubber, foam, suede, nylon, mesh and canvas to produce lighter, more comfortable kicks. You can still see people wearing shoes of that era, but likely not on your local running route. Saucony’s Originals line includes models it created in the ‘80s, like the one created for New York City Marathon champion Rod Dixon. You could certainly run in them, but you’re more likely to see these vintage designs paired with jeans than spandex.

Which brings us to now: If you can comfortably run in a shoe designed nearly 40 years ago, do you need to get a 2019 shoe?

The reason to go modern is to take advantage of the innovation that gives us faster, more comfortable shoes. Over the last four decades, shoe manufacturers have continued to refine their designs, sometimes with dramatic new products (see: Nike Zoom VaporFly 4%), other times with small tweaks to classic models (see: Nike Pegasus).

Today you can get shoes designed for durability, different terrain, lightness, support and responsiveness—sometimes all in the same shoe. You can even get smart shoes now, with internal sensors that give you data you can use as you work to improve performance. Even with all their differences, the thousands of running shoes on the market are alike in that they have at least one feature some people might prefer while running.

But for the sake of narrowing down the options, here are a few general categories running shoes fall into:

Road: A wide spectrum of shoes fall into this category, but common features include a relatively smooth outsole, generally made of rubber. Road shoes may have a thick or minimal midsole—the measurement is referred to as the stack height—and a variety of offsets (the difference between the heel height and the forefoot height). Some runners prefer a low drop, meaning the offset ranges from about 0-6mm, while others like the feel of a higher offset in the 8-12mm range.

Trail: Like road shoes, trail shoes come in all weights and profiles. The distinguishing factor is the outsole, which has a rough, grippy exterior designed to give a runner traction on technical terrain.

Stability: Also called a support shoe, stability models feature midsoles with varying material density and motion control systems. The intentional construction is designed to reduce excess foot motion, like pronation and supination, which may lead to injury.

Neutral: Neutral shoe models do not have motion control systems and are best for runners who supinate or show wear on the outside corner of the heel, in the center of the forefoot or the outside of the forefoot.

Racing: Generally lightweight with minimal cushion, racing flats are designed to maximize performance above all else. Track spikes also fall in the racing category.

How to Choose the Right Running Shoe

Decades of research and evolving shoe design hasn’t identified the “best” shoe for a runner’s foot. The minimalist craze that started in 2011 led to dozens of headlines about the advantages, and risks, of barefoot running. A few years later, maximalism boomed, raising the same questions.

In another few years, we’re likely to see another trend emerging in running shoes. Scientists and shoe companies will certainly continue trying to design products that improve performance and reduce injury, giving runners plenty of options for finding what works best on their feet. In fact, a 2015 study out of the University of Calgary suggests that comfort matters most in choosing a running shoe and staying injury-free.

You’re the best judge of what feels right on your feet when they’re pounding the pavement or trails. But having a little bit more knowledge about your own body and the technology and innovation behind a shoe, never hurts.