A friend of mine, Russel Ray, a very knowledgeable, experienced and professional Home Inspector working in the San Diego, California area posted a great series of information on a variety of cracks that can be commonly found in a home or other building structure.  In Orangeville, Caledon Township, King Township, and the many South Simcoe communities such as Alliston, Beeton, Tottenham, Rosemont, Colgan, Bond Head, Cookstown and the rural area in between there exists a wide variety of soil conditions from clay to sandy to organic rich to rocky and as wide a variety of building styles.

His series has great information that I encourage you to read if you have found cracks in your home and want to find out more information before you can make a determination whether to seek professional (and possibly expensive) advice from a structural engineer and/or whether such a crack is a potential "major" issue (which needs to be addressed) or merely cosmetic.

Part One - Every Building Structure has or will have cracks
Part Two - Foundation Stem Wall Cracks below a Solid Wall
Part Three - Cracks in a Concrete Slab Floor in a Garage
Part Four - "V", "W","X", or "Y" shaped cracks in a home
Part Five - Horizontal Cracks in Foundation Walls below grade
Part Six - Cracks in a raised foundation starting at an Opening
Part Seven - How Water can cause cracks
Part Eight - Cracks in an exterior non load-bearing surface
Part Nine - The effect of the wet/dry clay soil cycle on a foundation