Inline skates came onto the market in the 1970s. They look much more like skates with wheels than roller skates. Inline skates are available in skates with 3, 4 or 5 wheels, where the version with 5 wheels is increasingly being produced because the version with 4 wheels rolls harder in practice.
A big difference in skates is the length of the frame. The long frames can be compared to riding on speed skates and the short frames are more like riding on ice hockey skates. The long frames provide more stability in forward movement, while the short frames provide more maneuverability.
The new trend is also increasingly larger wheels, with wheels now being placed on inline skates in a size of 125mm. The advantage of larger wheels is lower rolling resistance and the fact that they roll more easily over poorer surfaces. This also increases comfort. 125mm is exceptional, but 110 or 100mm wheels are very common.
A disadvantage of large wheels is that the center of gravity is higher and the pressure or force on the ankle also increases. A high shoe supports the ankle. However, a low shoe gives more freedom of movement and with a low shoe you can sit deeper and make longer strokes.
When your feet have grown, you also buy inline skates for a long time. Invest in a pair of good skates with a shoe that fits well and that you can skate on for a few hours without any problems. If you don't use them for a few years, they will still fit.
When storing them, store them in the dark in a dry place. Sunlight ultimately destroys everything and both your wheels and shoes suffer from UV radiation.