KiCad is an open source software suite for electronic design automation (EDA). It facilitates the design of schematics for electronic circuits and their conversion to PCBs (printed circuit board) design. KiCad was orginally developed by Jean-Pierre Charras, and features an integrated environment for schematic capture and PCB layout design.
This Reference Manual focuses on CvPcb. There are other books in this series for tools like eeschema, pcbnew,...