To understand how we leave digital traces, it might help to look first at how we leave traces in the physical world.
Physical traces can be subtle, and created unintentionally: bootprints in the hallway or strands of hair on the furniture; footprints in the sand if we're lucky enough to be at the beach.
They can also be invisible - fingerprints, for example - or they can be visible and intentionally created: a handwritten postcard, or a form we've filled in to renew our passport. Like the subtle traces, they refer back to us in some way and reveal details about us.
In the digital world, things work sort of the same, but on a vastly bigger scale.
Most of us leave hundreds of digital traces every day. Like physical traces, some of these traces are intentional and visible. These include things like emails, texts, blog posts, twitter posts, photographs, comments under Youtube videos, or likes on Facebook. But many traces are invisible and unintentional: records of our website visits and searches, for example, or logs of our movements and phone calls.
Individual digital traces put together can offer huge insight into the details of our lives - including details that we had assumed were private.
Content and Metadata
To learn how digital traces are created, we need to differentiate between two types: content and metadata.
When you send your friend a text - "I just saw a newborn puppy" - this is the CONTENT of the message.
When the content is sent, additional information about the content is automatically created - in this case, a log of the two phone numbers involved, as well as the time the text was sent, and the location of both phones. This is the METADATA. Metadata is data about data.
The most common types of metadata are:
- Phone numbers, email addresses and usernames
- Location data: where your mobile phone is
- Date- and time-stamps on phone calls, emails, files, and photos.
- Information about the device you are using
- The subject lines of your emails
Why is metadata important?
We generate metadata unknowingly, in an organised format and over the long term. Metadata makes it easy to analyse, recognise patterns and draw conclusions about who we are, and what we are doing.
Companies that are central to our communications - like our mobile phone provider or internet/email service provider - have detailed logs of this metadata, and this gives them, and anyone else who can access this information, an unprecedentedly detailed picture.
Metadata can also reveal things we might not want to reveal. If our phone shows up in a certain location at the time that there is a protest, this can reveal that we were one of the protesters.