Illustration by Jørgen Stamp

In recent weeks, there has been a lot of talk about the metadata (the data about data) collected by the US government from our phone calls and emails. Clearly, metadata is a valuable source of information — sometimes just as valuable as the data it’s about!

All human rights activists who create or use digital content should have a basic understanding of metadata. Like any kind of information, it can be put to great use as documentation and evidence, or employed against people in nefarious ways.

Why do we have metadata? Metadata, like the date and sender of an email message, is necessary for the functioning of digital content. Every time we create digital content or data, we also generate metadata (that we may or may not see). Here’s a typical email header, which contains the metadata of an email message:

What about video? Video, like phone conversations and emails, is just another type of data that has metadata. For example, here is a not-very-interesting 10-second video that I shot with my iPhone:

The video itself does not tell you very much. But if you look at its metadata – here I used the open-source tool MediaInfo — you can see information such as where and when I recorded my video, what type of camera I used, among other things:

If I transfer this video to someone using Skype, the Skype metadata shows the details of my data transfer. Skype automatically saves this metadata on my computer, in a database located here:

Mac: /Users/[your user name]/Library/Application Support/Skype/[your Skype Name]/main.db

PC: %AppData%\Skype\[your Skype Name]\main.db

When I look in this database – here I used SQLite Manager, a Firefox add-on — I can see things like who I sent my video to, when I sent it to him (expressed in POSIX time), and which file I sent from my computer:

If I then upload my video to YouTube, I can see a lot of metadata on my video’s YouTube page, including my YouTube user name, the date I uploaded the video, and information I added like the title and description:

I can see even more of the underlying metadata about my YouTube upload if I use YouTube’s Data API (v. 2), such as when I last updated the YouTube page, page access settings, and other technical details:

As you can see, metadata is everywhere and we generate it all the time when we create, move, or use data. You may or may not ever need this information, but it is good to be aware that it is there, and to consider how you (or others) might use it.