PC originally stands for "Personal Computer" for electronics & was penned around the late 1970's & early 1980's when computers became small enough & affordable enough that people could purchase & utilize them for their personal needs & desires. Prior to the PC, computers were massive & expensive machines. The first computers were virtually the size of a building (at least taking up a floor of a building) & costing tens to hundreds of thousands of dollars to make. As technology improved, the cost & size came down (from entire floors to entire rooms, then the size of office desks before hitting the "desktop" size we're more familiar with) in the process.
Nowadays, PC typically refers to any laptop or desktop computer that is NOT an Apple computer & NOT running Mac OS (which, ironically, if a heavily modified form of Linux)... which makes the term a bit ubiquitous (effectively losing it's original meaning).