Antialiasing is a technique used to help reduce the appearance of the jagged stairstep of pixels that is encountered when drawing lines that are neither horizontal or vertical, usually most evident along highly contrasting edges. Antialiasing can reduce this problem by averaging the values of neighboring pixels, thus giving the appearance of a smoother transition from one color to another.
Edge antialiasing involves redrawing specified lines using antialiasing. This can be a very efficient way of antialiasing a few important edges without incurring any significant performance loss. Excessive use of this technique can be computationally expensive, so dont use this technique on every edge in the scene.
Enabling general antialiasing means that antialiasing will automatically be applied to all lines and polygons rendered in 3D scenes in the first pass, without any redrawing required. Some hardware requires sorted polygons to perform general antialiasing, this can be checked by looking at the flags in the RasterCaps property of the TD3DPrimCaps object.