Trading/Before Java Edition 1.8

Differences

 * Each robe had only one class of villager.
 * Villagers started with only one offer.
 * Trading would unlock up to one offer.
 * Trade order was randomized.
 * The locked trade icon appears without reopening the GUI and has a description.
 * Offers could be unlocked only by trading the final trade.
 * Trading did not give experience.
 * Villagers would ignore damage values.
 * Gold Ingots were used as a fallback offer; any time a villager randomly selects none of its offers, it would choose to buy gold ingots instead. This is why gold is offered so rarely as a trade, and also why it is the green villager's only item.
 * It was possible, when trading for an Enchanted Book with a librarian, that the cost in emeralds would exceed 64. This only happened with books containing tier 5 enchantments.
 * Trading was the only legitimate way to get Bottles O' Enchanting in survival mode.

Possible offers
The following table lists the minimum and maximum offers that a villager would make before 1.8 when buying and selling items.

Generic (green clothes)
''Note: The green Villager is only obtainable using /summon, server commands, mods, or third-party map editors. It doesn't spawn naturally, even when using a spawn egg.''