The word “backpack” is first recorded in 1896.
A backpack is a bag carried on the back and usually secured with two shoulder straps. The basic idea is much older than the English word: people have carried loads in sacks, packs, and other containers for centuries.
The term became especially useful as back-carried bags served hikers, travelers, soldiers, and eventually students. The related word “rucksack” comes from German, while “knapsack” was the usual English name for a rucksack until the middle of the 20th century.
Backpacks became strongly associated with school because they can carry books, stationery, lunch, and sports equipment while leaving the hands free. Modern school designs commonly include padded shoulder straps, several compartments, reinforcement, and reflective panels. The 1896 date refers specifically to the recorded English word, not to the invention of the bag itself.