Substitute Goods are those goods that can be used to satisfy the same necessity. Substitute Goods have a positive cross elasticity of demand. That is, when the price of one good increases, the quantity demanded of the other good increases, because the user can substitute one good for another.
Complementary goods, in contrast, have a negative cross elasticity of demand.
Examples of substitute goods are (more than 10 examples):
Graphical Analysis of Substitute Goods: