Identifier New
Namespace idNamespace idsNamespaced stringNamespaced stringsResource idResource idsResource locationResource locations
Identifiers are a way to declare and identify elements in Minecraft like items, block or entities.
Identifier can be made with lowercase letters (abc…), numbers (123…), underscore (_), hyphen (-) and dot (.).
Identifiers have this structure namespace:name, where the namespace is the name of the folder from the Datapack or Mod where the item is located, and the name is the name of the .json file where the resource is declared.
For exmaple, if I want to obtain a glass block using Commands I would type this:
/give @s minecraft:glassminecraft:glass is the identifier of the glass block and minecraft is, of course, the namespace of Vanilla items.
Minecraft Wiki