title: What is breadth-first search useful for?
body: <p>Usually when I've had to walk a graph, I've always used depth-first search because of the lower space complexity.  I've honestly never seen a situation that calls for a breadth-first search, although my experience <em>is</em> pretty limited.</p>
  
  <p>When does it make sense to use a breadth-first search?</p>
  
  <p><strong>UPDATE</strong>:  I suppose my answer <a href="https://stackoverflow.com/questions/1655162/how-do-i-partition-a-bipartite-graph-by-color/1657167#1657167">here</a> shows a situation where I've used a BFS (because I thought was a DFS).  I'm still curious to know though, why it was useful in this case.</p>