SoftAP is short for Software enabled Access Point. While a Wireless Access Point (WAP) is specifically made only to work as an Access Point, SoftAP is used to make a wireless client antenna work as both the Access Point and client.
How it works
The advantage of SoftAP is the use of a regular cellphone, for example, with a client antenna and data connection as an Access Point to serve other wireless devices which do not have a data connection otherwise. The wireless devices in the vicinity of the SoftAP enabled device, which may not have the Internet access directly, can use the Internet through the cellphone whose SoftAP is enabled. This is called tethering.
Various operating system platforms support SoftAP. Some of the operating systems which are known to support SoftAP are: