(Don’t laugh — the group also has ergonomic advice for toting purses, briefcases and suitcases.)

The first lightweight nylon backpacks appeared around 1967, designed by JanSport and Gerry Outdoors for use by hikers and, uh, backpackers. Soon, college kids started to adopt them. By the 1980s, backpack companies were making them specifically for textbooks.

The packs filtered down through the grades and around the world, replacing the book straps, satchels and schoolbags of earlier eras as an indelible part of a student’s identity.

That’s it for this briefing. See you next time. — Melina

Thank you

To Mark Josephson and Eleanor Stanford for the break from the news. Victoria Shannon, on the briefings team, wrote today’s Back Story. You can reach the team at briefing@nytimes.com.

P.S.

• We’re listening to “The Daily.” Our latest episode is the first of a two-part series about a new book about Harvey Weinstein by two Times reporters.

• Here’s today’s Mini Crossword puzzle, and a clue: Game for which there are more possible iterations than atoms in the universe (five letters) . You can find all our puzzles here.

• The Times’s Travel section has introduced a new column, Tripped Up, that offers advice on how to resolve travel disasters.