A plot is the general storyline of a piece of writing.
Plot is one of the key elements that makes a story either good or bad. A plot that is intricate and plausible without being predictable is generally a good plot. A plot that is boring, cliche, and senseless is a bad plot. Having no plot at all is also considered to be very bad.
However, one may have a good plot but use bad characterization, and the story will still be bad.