Just about all mobile phones (and some cameras) have a GPS-related function which adds location information to photographs. But my Pentax and Olympus DSLR cameras do not have the ability to tags photographs with that geotag location data.
In the last year or so when we were travelling in both Portugal and Sicily, I have I regretted not having that capability. I would take the occasional photo somewhere on a rural road, etc. with no real indication as to where we were (possibly I should have also taken a photograph using my phone or kept a diary)!
Until late last year, I had not noticed some photo editors allow you to merge GPS location data into the JPG photo data, based on the time a photograph was taken.
When out walking I often use Sports Tracker (Android/iPhone) on my mobile phone to log the route we’ve taken, time, distance, etc and I started extracting the geotags and adding them to some photographs. Sports Tracker logs points very frequently (approximately every seven seconds when walking) and so it can use a lot of battery resource if running all day.
I’ve recently come across the free Android GPSLogger which has settings so it can log positions at much longer intervals, not repeatedly log when stationary, and with different accuracy settings, so is more battery efficient, and will happily run for a whole day in background.
GPSLogger creates *.gpx files on the mobile phone which contain both position and time information (*.kml files only contain position). There is an associated Android program GPS Mapper & Report Generator which will display the *.gpx file on a normal or satellite Google Map on the phone. For Sports Tracker, you have to upload the data to your account on their web site and then extract the *.gpx file from it. GPXLogger has various options for sharing the *.gpx files; I just add them to my DropBox account so I can access them on any of our computers.
There are various programs which will add the geotags to digital *.jpg images (search for geotagging software). The GPSLogger web site also has some suggestions, e.g. the free Geosetter (for Windows). Of the Windows desktop image editors I have, I’ve found Zoner Photo Studio to be the easiest to use (the full version of the Zoner software is sometimes offered as a free download), especially as the program allows you to geotag images in bulk.
It is unlikely your camera clock is adding an accurate time to the JPG images so the merging software allows you to apply a time synchronisation for more accurate position tagging. It is just a matter of taking a photo of the clock on the phone/computer (displaying hh:mm:ss) to calculate the appropriate timing synchronisation adjustment based on the clock time and the JPG image time (surprisingly, I’ve found my camera clock time differences can vary by up to ten seconds over a few weeks – could this be battery charge or temperature effects?)
And finally, if you add location data to photographs, there may be times when you want to remove the information for privacy reasons. The desktop photo editors and other simple programs will allow you to do so.