Purpose of bookmark, imgcache and rev_geocoding files in cache? I have an Alcatel and on my Android internal storage in my cache has all of these files with question marks and I can't view them and these files are:

bookmark.0
bookmark.1
Bookmark.idx
img.cache.1
imgcache.idx
rev_geocoding.0
rev_geocoding(0).1
rev_geocoding(1).1
rev_geocoding(2).1
rev_geocoding(3).1
rev_geocoding(4).1
rev_geocoding(5).1
rev_geocoding(6).1


and they're all saying "file format not supported".  What does this mean what do these files mean and how can I view these files?
Those are cache files for specific apps and can usually only be read by the specific apps which they belong to.

If you really want to try to look at them (although they will probably not be readable by a human), you can install an app like ES File Explorer and open the file as a text file.