In general, handaxes are large stone cobbles which have been roughly worked into an oval or triangular shape. They are pointed, or at least pointy on one end, and some of those pointy ends are quite tapered. Some are triangular in cross-section, some are flat. In fact, there is a lot of variability within the category. And, definitely, early handaxes (made before about 450,000 years ago) are simpler than the later ones, which evidence finer flaking.
Acheulean Handaxe Distribution
The Acheulean handaxe is named after the St. Acheul archaeological site where they were first identified 150 years ago. The earliest handaxes have been dated about 1.6 million years ago in eastern and southern Africa, at sites such as Konso-Gardula in Ethiopia, Olduvai Gorge in Tanzania, and Sterkfontein in South Africa.Early handaxes have been associated with Homo ergaster (H. erectus) in Africa and Europe. The later ones seem to be associated with both H. erectus and archaic H. sapiens. Acheulean handaxes have been recovered from Africa, Europe, India, and (possibly) China.
Sources
Lycett, Stephen J. and Noreen von Cramon-Taubadel. in press. Acheulean variability and hominin dispersals: a model-bound approach. Journal of Archaeological Science in press.
Machin, A. J., R. T. Hosfield, and S. J. Mithen 2007 Why are some handaxes symmetrical? Testing the influence of handaxe morphology on butchery effectiveness. Journal of Archaeological Science 34:883-893.
Marshall, G.D., Gamble, C.S., Roe, D.A., and Dupplaw, D. 2002. Acheulian biface database.. ADS, York


