Pour the bottle of balsamic vinegar into an uncovered saucepan.
Heat over low to medium heat, stirring occasionally and constantly checking on the consistency of the vinegar. (Don't leave it unattended too long. Don't ask me how I know that! )
As the liquid begins to evaporate, the vinegar will become thicker and sweeter. Keep it at a low simmer. If you turn the heat up too high or leave it unattended too long, you'll end up with a burned, hard, mess at the bottom of your pan. (Don't ask how I know that.)
Once you have reached the desired thickness, after reducing by at least half, take your reduction off the heat and pour into a serving bottle.
Serve with salads or fruits, or however else you choose!