Minecraft wiki entry for Tag, associated text: 1 Usage
1.1 Resource location
1.2 Block tags
1.3 Item tags
1.4 Entity type tags
1.5 Function tags
2 JSON format
3 List of tags
3.1 Blocks
3.2 Entity types
3.3 Fluids
3.4 Game events
3.5 Items
3.6 Biomes
3.7 Structures
3.8 Flat level generator presets‌[upcoming: JE 1.19]
3.9 World presets‌[upcoming: JE 1.19]
4 History
5 Issues