Maybe this is a trivial question.
I am looking into a JSON file I found something like this:
{
    localization_id: 2,
    local_user_id: 33,
    is_active: true,
    registration_date: 2017-09-13 12:05:21
}
When looking into another JSON file otherwise I found something like this:
{
    "cod": "200",
    "message": 0.0036,
    "cnt": 40,
}
Why in the second one the field name and some value are into the ""? Is it irrelevant or have a meaning?
 
    