Acciaccatura vs Appoggiatura in Beethoven

1. How do you identify appoggiatura?
2. What is a short appoggiatura?
3. What is the point of appoggiatura?

How do you identify appoggiatura?

An appoggiatura is always "on the beat" or it doesn't deserve the name. If you see two notes that form a descending second, and the first is in an accented position and is approached by an upward leap, that is possibly an appoggiatura.

What is a short appoggiatura?

: a grace note performed very quickly, played either on the beat or before the beat, and symbolized by a small note with a stroke through the stem.

What is the point of appoggiatura?

An appoggiatura is a small grace note written to suspend the resolution of a chord. It takes half of the actual note's value, usually.