What are weighted and touch sensitive keys
Weighted keys are piano keys with a natural resistance. The keys feel heavier. This is due to the movement of the hammer mechanism of the piano.
With a real piano you feel resistance when pressing the keys because there are hammer mechanisms on the keys. When you press the key, the hammer strikes the string of the piano. In the bass region of a piano, the hammers are larger and the keys heavier. As you go up in sound, the hammers become smaller so that the keys feel lighter and lighter.
Velocity-sensitive keys are piano keys that come with a soft touch soft sound produce and at one harder touch harder sound produce. This allows both small and sensitive piano to be played and very loud.
A real piano is velocity sensitive because the hammers attached to the keys strike against the strings. You decide how hard or soft you press the piano keys and how much volume you produce.
Keys digital piano
Piano keys from a digital piano are made for the velocity and resistance of a real piano identical. Most digital pianos have 88 weighted and touch sensitive keys. Often the touch sensitivity of the keys can be set as desired. Also a digital piano plays heavier in the bass and lighter as you play higher.
If you have one digital piano want to go buy or whore, then it is important that the piano features 88 weighted and touch sensitive keys. In this way you immediately develop the right technique and it is a small step to eventually switch to a real piano.
Semi weighted keys
Semi-weighted keys are keys that have the same resistance over the entire keyboard. So there is no difference in the keys in terms of resistance. Digital pianos with semi-weighedkeys are attack-sensitive.
A semi-weighted keyboard is not the ideal keyboard to learn to play piano, but it's better than a keyboard.
Read also: How many keys does a piano have?