Piano tuning is the act of making minute adjustments to the
tensions of the strings of a piano to properly align the
intervals between their tones so that the instrument is in
tune.  The meaning of the term in tune in the context of
piano tuning is not simply a particular fixed set of pitches.
Fine piano tuning requires an assessment of the interaction
between notes, which is different for every piano, thus in
practice requiring slightly different pitches from any
theoretical standard. Pianos are usually tuned to a modified
version of the system called equal temperament In all
systems of tuning, every pitch may be derived from its
relationship to a chosen fixed pitch, which is usually A440.  
 
Affinity Piano Tuning