Official Resources

Blender Website
Official Blender Foundation Website
Downloads, news, and community resources
Documentation
Official Manual
Complete documentation and user manual

Learning Resources

Blender Guru
Tutorial Website
Popular tutorials including the famous donut tutorial
Blender Stack Exchange
Q&A Platform
Community-driven question and answer site
Kaizen
Youtube Blender Tutorial Channel
Mainly about lighting, setting up nice scenes and general Blender Stuff

Assets

Polyhaven
HDRI Collection
Free HDRIs, ever expanding.
Poliigon
Texture Library
High-quality materials and textures

Add-ons

Blender Market
Marketplace
Commercial add-ons and assets
Blender Exensions
Addon Listing
Listing of Addons available in Blender directly