Hi sakairiyoshimasa, Welcome to EasyEDA. A wire in a schematic is called a `net`. In the text description of a circuit, which is called the `netlist`, a 'net' is the list of all the things that are connected together by a wire. Find out more in [All simulation schematics MUST have a ground 01]. [All simulation schematics MUST have a ground 01]: https://easyeda.com/file_view_All-simulation-schematics-MUST-have-a-ground-01_y20YWvRPp.htm in the [Spice Tutorials] folder: [Spice Tutorials]: https://easyeda.com/project_view_Spice-tutorials_AysKEWevN.htm :)