Common Core is a set of shared academic standards, for English and math only. The idea is that U.S. students should all learn the same educational essentials, regardless of whether they live in Mississippi or Massachusetts. Common Core standards were created with an eye toward making American high school graduates more competitive with their international peers.
To me common core is a test where they make you do questions that most people in the targeted age do not understand. The teachers do not even try to explain to us the type of standardes we need to expect. Also most teachers get frustrated because takes up weeks of learning time.