How do you use Concentration?

[BladeofSharpness]

I mean practically, I know you hit the V key!

I use it mostly to see where I threw my spear.
It is also useful at night to light up a bit for a few seconds.
And that's mostly it. I'm not very imaginative probably...

[Enter the Wang]

Yes, it's mostly 'where is my spear'. In some cases, it's 40% chance of finding the jackal or boar that is stalking you (at 2 nd level) by finding the footprints.

[Raven]

Once you upgrade it a little more, it helps you track and find animals you've wounded that have run away. I used it a lot during the demo when hunting peccaries.

[Syriusz]

Running through snake/ scorpion/ spider infested places without worring about getting hit by them. It decreases my stress and make travel faster, since I don't have to slow down to search potential dangers, they will be clearly visible. It has to be upgraded to top tier, but it's worth it. Only thing that sucks is that I think sometimes snakes can spawn in front of you, because sometimes snake appeared few meters in front of me, usually when I was climbing the hill and it spawned on top. It can see through walls so it wasn't that.

[jessi81]

It also shows you special items nearby. Not sure which level of cocentration that was. Helpful, so you don't need to look at the map all the time.