As Jim said; the finer your resolution the more exacting your edits can be.
Try to edit at the zero point (where the line crosses the horizontal bar).
This stops clicks that happen from misalignment. Finer the Resolution, the finer you can edit. (However see below for the flip side of it)

Another tip is to make sure your check box for 'Smooth Audio Cuts' is enabled.
Any Cut/Copy/Paste routines then 'fake' the cut to cross at zero at the Start/End point.

Between those two things during the editing process you can eliminate a lot of it to begin with.

You can try 'Consolidate Audio', as mentioned also, but my gut says that will just make the edit marks go away, not the underlying issue. I don't think it smooths cuts, it just writes what you have as one long piece instead of those edited chunks. However it's worth trying as I've been wrong before (and jford has taught me new things before).

FWIW the edited chunks are what is needed for the Undo function. It marks the start/end of various edits. So if you start cutting into a previously edited section the start/end points are going to be off.

Flip Side
If all you use is RealTracks (or something with a strict click), some users like using the Bars window to select sections before editing them; then you know you always have exact measures.
But if you record live audio (bands or live instruments) this may not be effective, as humans are not 'right on' .. but RTs seem to edit as though they are most of the time.

Make your sound your own!
.. I do not work here, but the benefits are still awesome