The Nobel prize in economics was awarded to Leonid Hurwicz, Roger B. Myerson, and Eric S. Maskin in 2007 for \having laid the foundations of mechanism design theory". This article aims to explore these very foundations of mechanism design theory. In the process, it highlights one important contribution each of Myerson and Maskin, and describes some fundamental concepts of mechanism design, which are due to Hurwicz. While it briey describes Maskin’s Nash implementation work, it goes into the details of Myerson’s optimal auction design work, its extensions, and ongoing work.