Reward charts can monitor physical and mental tasks and behaviors. Perhaps it's a chore, like making their bed every day, or a behavioral issue, like not whining during dinner for a week. The subjects covered by the chart are totally at the discretion of the parent. In fact, the type of chart is also up to the parent. Be it simple or elaborate, a basic computer printout of goals or a fancier laminate chart available in stores, the important thing is just to have the chart.
Visual checkmarks show the child how far they've come. They can see how close they are to achieving the agreed-upon reward. The parent needs to make sure they follow through with the reward immediately upon the completion of the task, too. A child needs that positive reinforcement as soon as they see that final checkmark entered on the chart. It loses its punch if the reward comes two weeks later.
For children, a reward chart is a way to teach accountability. They learn and have fun with their rewards, and ultimately, the parent is rewarded as well by having a more pleasant parenting experience.