Seeing that the purchase of a home is probably the largest single investment that you you will ever make, you should learn as much as you can about the condition of the property before you commit to buying.
There can be a lot wrong with the house that may not be obvious on the surface, and unforeseen repair costs can run into the thousands. Its important to know what these issues are before the sale goes through. Trying to address these with the seller or agent after the sale is very difficult.
If you are a buyer: The inspection will tell you everything that is wrong with the house to that you can negotiate with the seller.
If you are a homeowner: The inspection will identify problems and recommend preventive measures which will prevent costly repairs in future.
If you a seller: The inspection will point out any major issues that you may want to address before putting the house on the market so that you can get the best possible price without over capitalizing.