I hear the term "expression" being thrown around a lot during class, such as, such and such protein is being expressed. What does that really mean? Is it just another way of saying that a certain protein is being synthesized by the cell, and is it confined only to certain molecules?
You're right -- gene expression means making the gene product (usually a protein, but sometimes a tRNA, rRNA, etc.) so the effects of the gene and its product are measurable, determinable, etc. Some genes are only "expressed" at certain times or in certain tissues (in a multicellular organism) -- under other conditions the genes are effectively mute.