The simplest transition from one shot to the next is the cut. The transition from one shot to the next occurs instantly, from one frame to the next. It is unobtrusive and by far the most common way to move from one shot to another.
There are times when a cut doesn't work. I was given a tape that someone else had shot. We were creating short videos (one or two minutes) for the website introducing each professor. It included a long, well-thought-out discourse by a professor. It was basically one long shot. Great stuff, but not what I needed. And there was no B-roll. There was nothing to cut away to so I could not extract a tight couple of minutes from the longer talk without leaving jump cuts.
Remember that we don't usually want ...