title: What is the difference between an entity set and an entity? Is this definition standard?
body: <p>I'm wondering if my textbook has a non-standard definition. I've red <a href="https://stackoverflow.com/questions/6162746/what-is-the-difference-between-an-entity-entity-set-and-attributes">this question</a> and it is not a duplicate. The book defines entities and entity sets as </p>
  
  <blockquote>
    <p>An entity is an abstract object of some sort, and a collection of
    similar entities forms an entity set. An entity is some ways resembles
    an "object" in the sense of object-oriented programing. Likewise, an entity set bears some
    resemblance to a class of objects.</p>
  </blockquote>
  
  <p>When they say "class of objects" are they referring to a class as in the thing you instantiate to make new objects (I know this is just a loose comparison). It sounds like an entity set is more general than just an entity, but in <a href="https://stackoverflow.com/questions/6162746/what-is-the-difference-between-an-entity-entity-set-and-attributes">this question</a> a reply states "An entity set usually represents a slice of an entities data" which is the opposite. </p>
  
  <p>I thought an entity is like a table in a database, then what's an entity set?</p>