What can I actually know?

The most common definition of knowledge, at least in philosophical circles, is: warranted true belief.

Your second Q is more difficult, in part because I cannot hear your inflection. Which term is being emphasized? I'll go for the broadest reading. You can only know anything by making a set or reasoned assumptions which must be themselves unprovable. Reasoning from these first principles, assuming you don't make a mistake, allows you to have rational certainty.

Your last question is also difficult because it involves pinning down the idea of warrant. Philosophers (epistemologists) wrangle about this as part of their professional lives. A common sense answer, which is certainly vulnerable to criticism, is that evidence warrants belief if any rational mind will draw the conclusion you do. Of course, this is ultimately self-referential. It seems to make all knowledge social. It also begs a bunch of other questions.

I confess I'm a bit puzzled by you asking these questions. I've seen your Q&A. You are surely philosophically sophisticated enough to have wrestled with this stuff for a long time at a serious level. Is there some point you're trying to make that I'm missing?

peace

I wasn't being critical. I was just wondering out loud (a bad habit). But your right. I should have e-mailed you rather that positing that as part of my response. My bad.

Knowledge is being aware and grasping the basic concept of how something works/does.

You cannot know anything because knowledge is a personal illusion.

The only thing you can know is that you are conscious as well as analytic truths - which are true by definition. E.g. I know a triangle has three sides.

The definition of knowing something usually means that knowledge is infallible and there isn't any possible room for doubt.

Study Epistemology. That is the branch of Philosophy dealing with those issues you have raised, which are beyond the scope of this forum.

Everything we know is from our senses, light photons, hearing vibrations ect. If we can feel something happening to us, it is up to us what we make of it. Do we all see the same blue?

Don't go too far down the rabbit hole because it might make you crazy

That is the domain of epistemology, a science so deep you can get a PhD in just that.

You know your existence because you can recognize the existence of a "self". Cogito, ergo sum.

Everything else is perception.

it's all sense-data my friend.. which you can rely on for perceived results in this world. other than that we know nothing..