The Necessary and Proper Clause refers to a section of the United States Constitution that grants Congress the authority to create and enforce laws that are deemed "necessary and proper" by the powers granted to the branches of the government by the Constitution's various provisions. The clause is found under Article 1, Section 8 of the Constitution.
The Constitution of the United States grants certain powers to the government, and these powers are often referred to as enumerated powers. During the Constitutional Convention, resolutions were drafted concerning these various powers. This was done essentially to ensure that the Constitution outlined what powers the government would be in its authority to use. The framers of the Constitution drafted the Necessary and Proper Clause for a similar reason: to establish the precedent that Congress can make laws that will carry out the authority vested to the central government by Constitution.
The Necessary and Proper Clause allows the government to do some very important things, like facilitate and organize the judiciary branch. During the formation of the U.S.'s central authority, this clause became very important as the government had to be organized and established, and this clause granted it the power to do so. The clause is important today, too, because it describes how the government can justify its authorities under the Constitution, a living document that many times has been the subject of interpretation.
The clause has been interpreted differently over the years, especially by the justices of the U.S. Supreme Court who presented varying ideas about how this clause should be used during the McCulloch v. Maryland case in 1819. Chief Justice John Marshall concluded that unless laws had a means-to-an-end justification, they simply couldn't be seen as constitutional.