In the 1400s, Tarot was a card game played in Italy. It had nothing to do with divination at all. It's gone through many revisions since then, especially as the cards spread to Germany and France, mainly changes to the names of the suits (coins/pentacles/discs/bells, cups/flowers, rods/sticks/wands, swords/pikes) and to the content of the trump cards (huge differences between regional versions). Modern tarot has settled on four suits of 14 cards (Ace-10 + four face cards, Knave, Knight, Queen, and King) and 22 trump cards (labeled 0-21), for a total of 78. Modern playing cards are based on this setup: diamonds (coins = money!), clubs (wands and sticks, hitting instruments), spades (swords. Something about a corruption of pikes and spears that looked like shovels to somebody), and hearts (cups and flowers. Love themes.) with the trump panoply being compressed into the number zero card, the Fool, as joker(s).
The cartomancy showed up in the 1800s, when French occultists claimed the cards had ancient ties to Egypt, I ching, Kabbalah, etc. Though there's evidence that the concept of playing cards arrived in Italy from China and the Mid East, modern tarot is so divorced from those origins that it's a major stretch. For looking into the divination symbolism I'd recommend the Rider-Waite card art; a lot of custom and ancient tarot sets have gorgeous art, but RW's art actually has the card's "meaning" symbolized in the image. All details below are therefore some combination of old card game fun folklore with a layer of 19th century French mysticism sprinkled on top. Plus I think knowing what the cards mean in a general sense makes references to them even more enjoyable; when you know that The Fool is supposed to represent beginnings, the Fool card in the Binding of Isaac teleporting you to the starter room...makes sense!
In the divination sense, the suit cards and trump cards are renamed the minor and major arcana. Without detailing individual cards, there are *themes* that go through the deck. Each suit represents a classical element and an aspect of life experience, which goes through a "journey" of ups and downs from Ace to 10. The face cards usually represent people connected to this; the page is an idealistic neophyte, knight is an overexcited crusader, queen is a wise and calm adept, king is a stern and commanding master.
Cups: water and emotions. You start at the ace with "new love! new thing that brings you passion and joy!", go through the honeymoon phase, a breakup of some kind, crying, moving on, and eventually coming out stronger for it.
Coins: Earth and materials. Ace starts as "New job. New house. New pile of money.", takes you through hard work to build things, not appreciating it and losing it all, then patiently rebuilding stronger than ever.
Swords: Air and thoughts. This is the suit people tend to hate because it has a lot of bad/sad cards. Starts you with new ideas, pretty quickly dives into disappointment and self-reflection, ends on existential crises and hitting rock bottom.
Wands: Fire and actions. Starts with taking charge and moving forward with a new (thing), includes exploring, learning new things, fighting battles (real or metaphorical), winning some, losing some, and sometimes carrying a bunch of baggage a long way.
The major arcana do something similar, but in a more generalized sense since they're not tied to a specific aspect of experience. You start fresh, thinking you're hot stuff. You end up good at some things. You fly too high a few times and get spanked back down. Learn something about caution and humility, discover that sometimes bad stuff just *happens*. Become wiser, pick yourself back up again, and eventually declare "yes, I think I've finally learned whatever lesson I was meant to here" in the final card.
Aside from that, I just love the symbolism and multiple meanings on a lot of the cards. The four of cups, for example:
Thanks for not working, image tags
it's the card that means "dissatisfaction, boredom, daydreaming". It depicts a man sitting by a tree, with a cloud next to him forming a hand holding out a golden cup that he's contemplating. But the card is the *four* of cups; there are three perfectly good cups
sitting right in front of him. In the art you have both "He's bored and using his imagination to help alleviate it!" alongside "he's bored but you can see it's actually ingratitude".
Eight of swords is another good one.
Guess these don't work inside hide blocks.
It means "feeling trapped, limited, forced into your lot". It depicts a woman tied up in bandages, blindfolded, barefoot with swords in the ground around her. But the card also means "victim mentality and excuses"; the bandages are actually tied pretty loosely, and the swords haphazardly arranged in a way that doesn't actually cage her in. She could pretty easily shake the bonds off, take the blindfold off, and walk away. The elements of multiple interpretations are really neat there.