The Branding Iron is an item which can be used as an alternative to vanilla name tags.
The branding iron can be crafted on a vanilla crafting table using 2 iron and one leather in a diagonal formation, with the leather in the center.
When you first right-click with the Branding Iron, a box will appear, in which you enter the name your Branding Iron will apply to any animals it is used on. Once this is done, you must heat the branding iron by right clicking a fire (lava doesn't work). After this, you may name up to 5 animals before you must reheat the Branding Iron. In order to change the name the Branding Iron applies, you must craft the tool with 1 Iron Ingot.