The best part is the cross, with a crucifix, with a rosette or sun disc below it. The remainder is usually filled with patterns of leaves, grapes or abstract knotwork patterns. Occasionally it is surmounted by a cornice with biblical or saints' characters.
The most common reason for erecting a khachkar was for bad reasons - for the salvation of the soul of either a living or a dead person. They were also removed for other reasons, such as to praise a military victory, construction of a church, or as a protection from natural disasters.
A lot of khachkars are in graveyards. But Armenian gravestones take many other forms, and only a small are khatchkars.