Legal question regarding caching & composition

Hi,

Legal guidelines regarding the use of Web Snapshots are hard to find, so this is why I'm asking the following:

a) Is it allowed to cache images on your own server. If not, what about the scenario where a snapshot gets crawled and then cached by google or facebook (when shared as a preview image on a timeline for example)

b) Is it allowed to compose additional graphics on a snapshot, that being only possible if (a), the possibility to serve a local snapshot is given.
Legal question regarding caching & composition
 
 
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