What are the effects of changes in price on demand and supply?

If you are using economic terms precisely, a change in the
price of a good or service does not affect the demand for or supply of that product.  It
will affect the quantity demanded or supplied but not the
actual demand or supply.  It will, in other words, cause a movement
along a curve, but will not move the
curve.

An actual change in supply or demand
must be caused by some other factor.  For example, people may come to demand more milk
if a study comes out showing milk prevents cancer.  There are ways in which the price of
a good or service can impact demand or supply of another product.  For example, an
increase in the price of McDonald's burgers might cause people to demand more of what
are called "competing goods."  That is, they might demand more Burger King burgers or
more pizza because the price of McDonald's has risen.

So,
to be precise, the change in the price of a good cannot change the supply or demand for
that good.