An intro to Warhammer 40K

To preface Warhammer 40k is an expanisve universe and can be scary going in although that should not deter and really you should go at your own pace

Also I follow the humanity side a bit more than the rest of the universe but the other factions also have some fleshed out lore

Warhammer 40k is set in the year 40 thousand and everything sucks
Humanity is a zealtous cult worshiping a man who does not want to be worshipped by zealtous super soldiers who are considered angels, Battle nuns who's faith is their strongest weapon, and the ten's of billions of Men and Women who are willing to die for their God Emperor

They face the threats of Tyranid bug monsters who eat everything and outnumber them
Eldar space elves who want to survive and that means defending themselves from humanity
Orks who just want to kill everything or in other terms WAGGGGGGGGGH
Necrons who are space mummies who also have their souls stolen and are in metal skeleton suits who awaken in metal sarcophagi if they die.
And also Heretic traitors who turned against humanity for their own gods.

Here are some youtubers I recomend along with some of their videos