The main idea of this case was that racial segregation in public schools was against the Constitution. Before this case, the Supreme Court had ruled that states could segregate black and white people. They could do this as long as the facilities they offered the races were equal to one another. In Brown, the Supreme Court ruled that separate facilities could never be equal at least when it came to the public schools. This forced states throughout the South to change their laws that had prevented black children from attending school with white children.
The main idea of this case would be its ruling. "Separate but equal" was declared unconstitutional, It declared that public school segregation is a denial of equal protection of the laws under the fourteenth amendment. This was the most important supreme court decision in the decade following WWII.