Activity Definition vs Context Fields

Click a highlighted field to see which question it answers.
{
  "object": {
    "id": "https://dmccreary.github.io/lrs/sims/sine-wave/",
    "definition": {
      "type": "http://adlnet.gov/expapi/activities/simulation",
      "name": { "en-US": "Sine Wave Explorer" }
    }
  },
  "context": {
    "registration": "a94e...c2f1",
    "revision": "v2.4",
    "platform": "Intelligent Textbook Web"
  }
}
Each colored field answers one question. Green = the Activity Definition (describes the activity itself); purple = Context (the circumstances around this occurrence).
Activity Definition Context