hot spot

noun

1. 1.An optical phenomenon which creates a bright spot around the shadow of the viewer's head, when the surface on which the shadow falls has special optical characteristics (as with dewy grass).
2. 2.A place notable for a high level of activity or danger.
3. 3.A part of an application that consumes a significant amount of execution time.
4. 4.Part of a control that responds dynamically as the user moves the pointer over it, as for example in an image map.
5. 5.A location in which WiFi Internet access is available.