Hey everyone thanks so much for the feedback! I really appreciate it.

I still don't understand a lot of the fundamentals but knowing the difference between a solid and joined surface is very helpful!

Sorry for the short reply, but basically I mean, the mesh WAS a solid, and then at a certain point via booleans or some other reason, when I boolean out anything now, the mesh will create a hole, and the boolean no longer keeps the mesh a solid. I want to boolean out a bunch of surface details and extra form changes. The problem is I cannot go any farther now.

I have had this happen with every solid I have worked with, where at some point while I am working booleans break it. I don't have the proper vocabulary to really describe my problem so I am doing my best.

SO I get that I can still boolean, I just want it to stay a solid all the time. And i don't know at what point it breaks or if it's something I'm doing.
I booleaned this cube, I would ideally want this to be a solid. I know the mesh now longer is a solid but I know that people have had this issue, and could I fix this and make it solid again or fix this in the future?

As I said the person I knew said there is nothing you can do about it but I wanted to see what you guys think. He said he saves a lot because of this.