A WiFi Heatmap is a heatmap showing the strength and coverage of wireless signals in an area. A WiFi Heatmap typically shows the coverage of wireless signals on a real map of a room, floor, or house.
The reason why WiFi Heatmaps are used is that they tell you about the wireless coverage in a specific area and help you to find dead zones. Based on dead zones, you can then optimize your wireless network to achieve full coverage in the area. Without WiFi Heatmap it becomes difficult to achieve the desired coverage and involves a lot of guesswork as you don’t know exactly which place is a dead zone.