Users.metadata.json

Hi
Could someone explain what is metadata file for?
What is “uuid” ? (I used users.metadata.json from old “mflix-python.zip” to create index in the updated *.zip file, and it seems it works despite of uuid are different )
thanks,

{“options”:{},
“indexes”:[{“v”:2,
“key”:{"_id":1},
“name”:“id”,
“ns”:“mflix.users”},
{“v”:2,
“unique”:true,
“key”:{“email”:1},
“name”:“email_1”,
“ns”:“mflix.users”}],
“uuid”:“00c09377848e47cb99013f65b60e3938”}

It’s what MongoDB will use to restore metadata information about a collection. Looking at that I see two indexes specified that should be restored, _id which is given, and email which has a unique constraint on it.