The common Egyptian used a shorthand form of writing called hieratics. It derived from hieroglyphics but was used alongside it (it didn't replace hieroglyphics). While the monument carvers still used hieroglyphics, merchants and traders and everyone else was using hieratics to write their grocery lists and love notes.
The priests and scribes would often use both hieroglyphics and hieratic in important documents and religious texts, like you can see in the example above (hieratics make up the main body of thetext on the bottom, but hieroglyphs are used on the top of the picture). They would usually write these documents on papyrus, a type of woven paper, or sometimes on animal skins--both of which were time consuming to make and therefor expensive. But the common people, the laborers and farmers and traders, if they could write wrote their hieratic notes on flat limestone rocks, and broken bits of pottery, which were cheap and readily available.