title: What is a persistence engine (like ActiveRecord)? Advantages? Disadvantages?
body: <p>I've heard all this talk about Rail's persistence engine (ActiveRecord). I did a search on it and I couldn't really get a clear idea of what it did. It seemed like it was an Object mapping to a database but that's all I came up with. If so do they save the objects to the database to maintain persistence? What are the advantages of using this model? What are the disadvantages?</p>
  
  <p>Thanks!
  Matt Mueller</p>