What is the National Security Council and what does it do?

What will be an ideal response?

An ideal response will:
1, Describe the National Security Council as a council that makes policy recommendations and oversees implementation of foreign policy decisions, and as the president's most important source of advice about foreign policy problems.
2, Discuss how former presidents created smaller groups from the council to rely on during crisis situations, but how President Obama has significantly expanded the structure to add other staff people to the council (e.g., the attorney general, secretary of Homeland Security, and others).