What is the purpose of a time tracking software?

For an individual, time tracking software help to track the time spend on each task and projects. It helps to increase the productivity of an individual . For an organization, time tracking software helps to track the time spend by their employees on particular project or task and their work logs. I use Invoicera, an online application, for tracking time of my team and keep the track of work done by my team. Would like to recommend it to all.