At junior school cigarette cards, like conkers, occupied much of our playtime. Aged 9 or 10, we collected them, traded them, and gambled with them. They were cards that originally came in cigarette packets, hence the name. They measured, I suppose, about 3 inches by 1.5 inches, brightly coloured, with pictures on one side and a description on the back. Some depicted sports stars, whereas other series might feature famous ships, railway engines or aircraft. There were albums you could buy to stick them in, like a stamp collection. The boys all avidly collected them or traded them.
The gambling games included one where the first player would flick one onto the ground a few feet away. The second player tried to land his card so that part of it landed on top of the other one. If it did, he won it. If it missed, the first player retrieved his card and tried to flick it to cover part of his opponent's card. They took turns until a card was won. In another game a player would stuff cards between the pages of a book, and his opponent would slide a card into the book, hoping to hit a page that contained one. If he did, he won the card. If not, his own card was left in the book.
The cards were currency, to be traded, perhaps for sweets. I believe they started being issued in the last quarter of the 19th century, but disappeared during a World War II paper shortage and never really came back. The ones we traded might have been pre-war. There probably are elderly collectors today who have albums of them in their attics.