From what I've read, it seems VBOs are purely for performance.

I'm working on a very rudimentary learning project in lwjgl and I'm just trying to figure out what more advanced features of the library I should be delving into, and what their use is.

My understanding is that VBOs allow a person to keep vertexes in VRAM while they aren't currently being drawn in a scene. In my case, I'm just drawing quads and performance probably isn't a concern at all, but I'm trying to piece together what's happening under the hood. If I'm drawing quads directly, I'm drawing from the CPU memory, correct? Also, if I'm not doing any checks for visibility, does that mean I'm rendering absolutely everything in the "scene", regardless of whether its in view? Are VBOs a way to store objects and only render what's needed?