Minecart rail systems in Minecraft: powered rails, stations
The Minecart Improvements experiment (with its "Minecart max speed" game rule) also changes everything below.

The Minecart is a rideable cart made from five iron ingots. Placed on rails, it carries you, a mob or goods along a track, and combined with a chest, a hopper, a furnace or TNT it becomes one of four special carts.
It is made with the Crafting Table from 5 × Iron Ingot.
Use an empty minecart on rails to sit in it, and sneak to get out. A push starts it, slopes speed it up, and Powered Rails boost it when powered and brake it when not. Mobs that get pushed into an empty cart sit down in it, which is a common way to move villagers to a new home.
Combining the minecart with a chest gives a Minecart with Chest for moving items, with a hopper a Minecart with Hopper that collects items from blocks above it, with a furnace a Minecart with Furnace that pushes itself when fueled, and with TNT a Minecart with TNT that explodes on an activator rail.
Minecarts do not stack, so each one takes a slot. Breaking one returns the cart, and abandoned mineshafts hide chest minecarts along their tracks.
5 × Iron Ingot → Minecart
// Slots with several items cycle through every accepted option.
The Minecart Improvements experiment (with its "Minecart max speed" game rule) also changes everything below.
Each hopper takes items out of the minecart above it.
push them in a boat or a Minecart, or build the pen around two villagers in a village.
At night, bring an adult zombie with empty hands in a Minecart on rails (or in a boat), stop above the open centre column and break the cart:
At the Crafting Table: 5 × Iron Ingot give 1 × Minecart.
It carries players and mobs on rails and is the base of the chest, hopper, furnace and TNT minecarts. It is an ingredient in 4 recipes, made at the Crafting Table; for example Minecart with TNT.
No: only one per inventory slot.