What are the 4 main areas of employment in the it field?

What is estimated time of arrival (eta)? a device that measures the acceleration (the rate of change of velocity) of an item and is used to track truck speeds or taxi cab speeds a gps technology adventure game that posts the longitude and latitude location for an item on the internet for users to find a north/south measurement of position the time of day of an expected arrival at a certain destination and is typically used for navigation applications