The Abelian sandpile model of Bak, Tang, and Wiesenfeld has been a subject of great interest in the mathematics and physics communities since 1987. After introducing the model, surveying some standard results and unanswered questions, we will discuss in particular the recent works of Fey, Levine, and Peres; and Levine, Pegden, and Smart. Both make use of a least action principle, which...