If you notice, you focused on the tree branch. User error means you intended to focus on the squirrel but focused on the tree itself. Front focusing means that your camera meant to focus on the squirrel, but the lens isn't calibrated so it always focuses a little bit in front.

I understood the part where it could be my fault, but I did not understand the front focusing thing. Most likely a user error. How the hell am I even supposed to know if my lens needs calibrating or not, most likely my mistake.

If you actually focused on the tree branch, then your lens is okay. If you were actually trying to focus on the squirrel, then your lens is front focusing since if you were really trying to focus on the squirrel, it focused on a subject.

There are focusing charts you can print out and take a picture of which would tell you if your lens is focusing on the right spot.

In this situation, I am highly certain its just user error since I'm guessing you used center point and probably focused on that branch

I didn't use any particular points on my camera, it was automatically choosing for me, so I am sure it was a user error as well. I never gave it all my effort to get it in focus, either. You could say I was in a rush, because I wasn't sure how long he was going to stare at me for and I liked the expression I hope my lens is alright.

I like the picture a lot.

What about it do you like? I wasn't very happy that the lil squirrel wasn't the one in complete focus