Google last week introduced a new feature in Google Maps called Your Timeline. It’s Google’s latest attempt to show users what it knows about where they’ve been.

The last time Google did this — with Google Latitude — users could share such personal information with others. This time around, that’s not possible. It’s private — just as Google Photos, unlike the old Google+ Photos, wasn’t explicitly designed to be used for sharing. Indeed, Google Photos is fun to use for your own personal archival purposes, and people might well find themselves saying the same thing about the new Your Timeline service.

The only trouble is, if Google can accurately reflect where you’ve been, things could get a little spooky.

Image Credit: Screenshot

The facts

Without any input from you, Your Timeline shows where it thinks you’ve been, when you arrived at and left each place, and how you traveled from one place to another. The service highlights the days you visited the most places, figures out which places you visit most frequently, and clusters days out of town into “trips.” The human intervention comes in confirming or correcting specific places you go, and your mode of transportation for each trip. You can delete a place where Google says you’ve been — but even when you do that, the map will show that you passed by that area.

Google knows what it knows because you’ve asked for directions to certain places, and through location services on your phone’s Google Maps app (currently only the Android version), it has a more passive record of where your phone has been. From there, it can construct a timeline for each day. You can always delete all location history through the “Manage location settings” option in Your Timeline inside the Google Maps app on Android. Or you can click the “Pause location history” button on Your Timeline to stop Google from knowing where your phone goes.

And sometimes, the data is just wrong. Like the day I went from the VentureBeat office to a friend’s house a few months ago. The house is in the northern part of San Francisco, but my Timeline shows a line going to the North Bay that night. I try not to dwell on those cases of outright errors. They don’t happen that often.

Image Credit: Screenshot

It’s worth it to spend some time and brainpower checking each day in Your Timeline. As you correct data and confirm you were places it thinks you were, you see the bar chart of days changing. The gray area gradually decreases and is replaced with a pleasant blue.

If it can’t figure out for sure the name of the place you visited, it displays a generic neighborhood label. For example, when I was at the 24th Street-Mission BART station, it showed that I was in “Mission District” — until I corrected it by selecting “24th Street BART Station” from among the top options in the dropdown menu for that location.

Image Credit: Screenshot

On an Android device, it’s really interesting that Google gives you so many options to tell it how you got from point A to point B. Some are perfectly reasonable, and others are, well, edge cases.

Fascinating

To wit: moving, walking, running, cycling, driving/on public transport, by wheelchair, flying, driving, on a bus, in a tram, on the subway, in a train, on a ferry, in a cable car, on a funicular (had to look that one up), hiking, horseback riding, kayaking, kitesurfing (what? really?), Nordic walking (!), rowing, sailing, skateboarding, skating, skiing, swimming, sledding, snowboarding, snowmobiling, snowshoeing, surfing, motorcycling, and boating.

That level of customization promotes creativity. If I ever get the chance to take a snowmobile to work, I’m doing it.

What is unquestionably nice about Your Timeline is its use of your pictures from Google Photos.

Your Timeline breaks up the flow of each day with a few photos and connects them with specific dates, times, and places. It makes you appreciate and think about the photos and do new things with them — like share them, edit them, look up something that they make you think of, or reach out to someone you hadn’t spoken with in a while.

Image Credit: Screenshot

As you might expect, you can click on images and see them really big on your monitor — and, of course, you can disassociate them from a location you visit, too. (It would be interesting to see if Google tries to push data from Your Timeline into the Google Photos app, but for now the exchange of user data is only flowing in the opposite direction.)

Going back in time to specific days was cool, because it reminded me of a lot of great memories.

In that sense, it does a better job of journaling activities than I do on my own, and it’s certainly more visually compelling than Google Calendar, especially on desktop.

Your Timeline also reminds you of when you’ve been to a place in the past. Here’s what I saw when I looked up the address of a place where I was heading the other night:

Image Credit: Screenshot

When I tapped on “You visited 8 months ago,” I see the timeline for the day I was there last. In this case, I knew I’d been to Schroeder’s in the past, but I didn’t remember exactly when. Now it’s easy to see, right from within Google Maps.

Conveniently, you can download the geolocation data underlying Your Timeline.

Here’s how the raw data looks in JSON format:

Image Credit: Screenshot

Notice the numbers for “accuracy” for the latitude and longitude of locations, as well as “confidence” numbers for methods of travel. It’s not clear how user-submitted updates impact this data.

…But also a little freaky

The introduction of Your Timeline introduces new privacy and security implications that potential users may want to keep in mind.

Google already knows where you go, and when you make corrections, you’re providing Google with an even more accurate data set. It’s not clear how Google will use this data, in aggregate or for each person. But Google does now know which businesses I frequent, and when.

Image Credit: Screenshot

Meanwhile, if you’re not careful, someone may stumble across this data on one of your devices. That could be a curious current or former partner, or a concerned relative.

Notice how in the web version of Your Timeline, you can hover over the little lock icon on the top left, next to the word “Timeline,” and the words “Visible only to you” appear inside a floating black box. Clicking the lock does not trigger a pull-down menu, for now. But it’s not hard to imagine it becoming clickable one day, allowing you to share your authorized, confirmed whereabouts — maybe with whomever has the link, maybe with whomever you share Your Timeline, like the sharing permissions in Google Drive.

To be sure, you can’t do this right now, and you might not ever be able to.

For now, to access Your Timeline, go to Google Maps on desktop, hit the dropdown menu, go to “History,” hit the dropdown menu, and select “Location history.” Or just try going here.