title: What are Finite State Automata and why should a programmer know about them?
body: <p>Erm - what the question said. It's something I keep hearing about, but I've not got round to looking into it yet.</p>
  
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  <p>(updated) I could look up the definition... but why not (as pointed out by @erikson) get insight into your real experiences and anecdotes. Community Wiki'd incase that helps folks vote up the most insightful answer. Interesting reading so far, thanks!</p>