The magical space folding is an Enchantment.
It creates space, when there was only some using a reverse expanding charm. The idea behind it was used to actively hide the Hogwarts express and the train track from muggles. Invented by Lord Woodson Hawking in the 19th century. In the end a 800 km and 5 meter wide line hid the train and track with the help of 32,000 miniature wardstones, two placed every five meters. Whenever anyone crossed the five meter wide slice of land that contained the Hogwarts Express line, they bent themselves through an undetectable, space-contraction ward, none the wiser of what just happened. The wards are placed below the track and create a ward tunnel.
[ v ]Enchantments
|Dynamic space expansion · Earpiece communication mirrors · Granger magic trunk engine · Magical space folding · Weasley family clock|
[ v ]Human magic
|Wand based||Alchemy · Charms · Duelling · Transfiguration · Wand lore|
|Wandless||Enchantments · Herbology · Necromancy · Potions · Rituals|
|Mixed||Divination · Healing · Magical theory · Mind magic|