Named Binary Tag/1.17

Information between two points are passed in many different ways in Minecraft. The most common of them is known as NBTs. NBTs are a structured binary file used to store information on the disk. They are also used as intermediaries to hold information that will be sent across a network. Understanding and utilizing NBTs properly is a good start to understanding disk storage in general.

NBT Types

There are a total of fourteen different nbt data types that can be parsed. The most common one to use is CompoundTags within a BlockEntity or Entity when it comes to writing to the disk. However, on capabilities, other types can be specified to reduce the space it takes on a file.

All types implement Tag in some fashion. This interface holds basic methods for writing to a file and copying itself. It also holds basic methods to determine the output to a chat line.

Id	Name	Description
0	EndTag	Specifies the end of an nbt file.
1	ByteTag	Holds a byte. Also used to store a boolean value.
2	ShortTag	Holds a short.
3	IntTag	Holds an integer.
4	LongTag	Holds a long.
5	FloatTag	Holds a float.
6	DoubleTag	Holds a double.
7	ByteArrayTag	Holds a byte array. Can be parsed from an array of primitive bytes or a list of byte objects.
8	StringTag	Holds a string.
9	ListTag	Holds a list of a specific Tag.
10	CompoundTag	Holds an object comprised of Tags. It works similarly to a java object where it can store other primitives, objects, or itself inside.
11	IntArrayTag	Holds an integer array. Can be parsed from an array of primitive integers or a list of integer objects.
12	LongArrayTag	Holds an long array. Can be parsed from an array of primitive long, a list of long objects, or a LongSet.
99	NumericTag	Holds a generic number. Used when the specific Tag for a number is not specified. All numbers can be converted to each other.

In most cases, you will only have to deal with CompoundTag and ListTag. The others are usually handled internally by whichever type uses them.

Common Usages

CompoundTags are used similar to objects. You can put and value within them using a key. You can then retrieve the value once again with that same key. It has specific methods for putting and getting most of the different types of data (e.g. an integer using putInt and getInt).

ListTags are functionally the same as ArrayLists. You can add, remove, set, or get a specific NBT type.