If you look up technique in a dictionary it will say something like
Main Entry: tech·nique
Pronunciation: tek-'nEk
Function: noun
Etymology: French, from technique technical, from Greek technikos
1 : the manner in which technical details are treated (as by a writer) or basic physical movements are used (as by a dancer); also : ability to treat such details or use such movements <good piano technique>
2 a : a body of technical methods (as in a craft or in scientific research) b : a method of accomplishing a desired aim
so, referring to piano I would say....
1 you should be able to perfectly balance your arms and hands without playing the notes or feeling any tension at all.
2 Fingers should be naturally curved, playing on the tips of the fingers or fleshy part next to your fingernails (keep your fingernails trimmed).
3 Knuckles should not be caved in or too high. Knuckles could be fairly flat, but just slightly up, like a bridge. The same with the wrists and elbows.
4 Wrists should be even with the white keys, never too high or low
5 Elbows should be out from the body, allowing the weight of your arm to travel freely to your wrists and allowing for horizontal movement across the keys.
6 Always sit up straight, shoulders back, create a small arch in the middle of your back. Imagine a string going up through the center of your body, out of your head. Your pelvic bone slightly turned in towards the piano
7 You should sit far enough from the piano so that your elbows are slightly towards the front of your chest.
I also count the ability to play any technical difficulty you may come across at your level both loudly, softly, legato,staccato as part of technique (if I made any sense...), and also pedalling, fingering, etc
There are some essays on piano technique that I found on the internet, you might find them interesting...
theyre here
http://www3.sympatico.ca/norma.barr/library/piano/index.htmlHope this helps.....