Where you meet it
You meet the preview wherever the suite shows a file — in Files, from a mail attachment, from a link — framed inside the application you came from. The preview draws nothing around the content: no title, border, toolbar or actions belong to the application that opened it.
Documents that hold back
A document can name pictures that live elsewhere on the web — and until you say so, they are not fetched. A document that holds remote images says so, with a bar offering to Show remote images for that document. Nothing in a document can switch this on by itself; nothing in a previewed document can run.
What to know
- Nothing is rendered on a server. What you see was drawn by your own browser from the file's bytes.
- A renderer sees only the one file it was handed, in a frame that cannot reach the suite's cookies or storage or fetch anything; it dies with the file.
- Office documents open read-only in the editor provider, as far as the file allows — a launch may narrow what the file allows, never widen it.
- If a format cannot be drawn, the application you came from typically offers the download instead.
Next chapters
Files, where most previews start, and the rest of the manual: