Precision is the number of decimal places. For example a precision of two would be represented as 3.14, and a precision of three would be represented as 3.141.
Virtual Weather Station allows you to customize the precision for each variable (unless otherwise noted on specific display panels). These precision values are represented in files, HTML tags and other various displays.
The precision can be changed for the values (which include averages) and rates of change. Changing the precision for the temperature will change all of the temperatures (example, indoor and outdoor).