The 10th amendment states that the powers not delegated to the united states by the constitution, nor prohibited by it too the states, are reserved to the states respectively or to the people.
The purpose of the 10th amendment is to define the establishment and division of power between the federal government and states governments. This amendment also protects these powers from both entities.
My own words
The 10th amendment basically states that there are rights for the states so federal government cant take or abuse them.
Here are some supreme court cases
the slaughterhouse of 1873
Butchers and live stock producers who did not work for this company sued the state.
supreme court said that the case strengthen the 10th amendment
"Tenth Amendment." Constitutional Amendments: From Freedom of Speech to Flag Burning. 2nd ed. Vol. 2. Detroit: UXL, 2008. Gale Virtual Reference Library. Web. 10 Dec. 2015