Answer 1

https://www.w3schools.com/whatis/whatis_json.asp

Answer 2

data is a JSON object. Its contents are accessed using dot notation. So
data.explanation
accesses the data in the explanation field of the JSON object.

Answer 3

JSON is a format for saving data. It's very simple and very popular. You should take a look at it.

Answer 4

The call to the API fetches a JSON object. This is often the case for data APIs. This object is then assigned to the data variable for further manipulation.
https://www.digitalocean.com/community/tutorials/how-to-work-with-json-in-javascript

Answer 5

In the code three fields of the JSON object are accessed: explanation, title, and url.

Answer 6

So the JSON object looks probably something like this:
{"explanation": "some text",
"title": "some text",
"url": "an image url"}

Answer 7

You can see the full JSON file here:
https://api.nasa.gov/planetary/apod?api_key=XA6IuMbstRjVQf0EFkp2cdhQPOB4QuLhsMZUu4B5

Answer 8

That's lines 27-28. With the API's url in line 23.

Answer 9

You're welcome.

Answer 10

They used the .json() method instead:
https://developer.mozilla.org/en-US/docs/Web/API/Response/json