Sweating is a normal and healthy process.The average person produces about a litre of sweat a day[1] without even trying. Add in a few workouts and that figure can creep up to 10 litres of sweat a day. From just one person. Whilst working up a sweat can be good, it can cause embarrassing body odour and leave annoying stains on your favourite clothes.
[1] http://www.webmd.com/skin-problems-and-treatments/features/how-much-sweating-is-too-much