What is a Jump Ring Tool and how do I use it?

Jump Ring ToolSome chainmaillers prefer to use a combination of tools when weaving, for example one pair of pliers and a jump ring tool

Most people who like the tool use it primarily for pre-opening rings. Slip the jump ring tool onto the index or middle finger of your non-dominant hand. Use the pliers in your dominant hand to scoop up a jump ring. Still holding onto the ring with your pliers, insert the ring into one of the grooves in the jump ring tool. Then rotate your finger (with the jump ring tool) and the pliers in opposite directions to open the jump ring. 

Other maillers also use the ring for closing, but this can become difficult if you are trying to add a weave to a very dense weave and there isn't enough space for the jump ring tool.