The term "scratch" can refer to several different meanings depending on its context.
1) In a general sense, it could be used as an idiomatic expression which means something is not possible or feasible; for example, "I don't think that idea will fly - it's just a scratch."
2) It can also refer to the act of making short, shallow grooves in a surface using a sharp object such as a knife or pen. This action is often used when writing on surfaces like wood, plastic, metal, etc., and is commonly known as "writing with a pen" or "drawing with a knife."
3) In music, the term can refer to an unprofessional recording made using basic equipment, usually recorded in one take without any possibility of editing. It's often used when referring to homemade recordings that are not meant for commercial release.
4) Finally, "scratch" could also be a slang word for money - specifically the amount of money needed to start an activity or project; for example, "It will cost you $100 just to scratch."