So what exactly is My Activity?
It's basically a timeline that shows you what Google has saved about your online activities going back as far as Google has been tracking them. You can find it by going to myactivity.google.com. (Note: You'll probably be prompted to reenter your password as a security measure.) Once you've made it in, there should be a big chronological list of things you've done using Google's services — the searches you've made, videos you've watched on YouTube, and so on (assuming you haven't already used Google's privacy controls to block the collection of certain information, of course).
You can even search through the data trove to look up a specific record or activity Google has saved — like maybe the time you searched for a home remedy for plantar warts — or filter the timeline by date or type of activity.
And you said I could delete things?
Yup! If you don't want Google remembering that plantar warts search or when you binged watched videos of a cat in a shark costume riding a Roomba, it's pretty simple to erase. First, you need to find the record you want to delete, which is made easy with the search bar at the top of the page. Once you've found the shameful bit of your online past in the timeline, you can open a little menu by clicking on the three vertical dots on the right end of the record. Select the delete option on that menu, and voila — Google will forget it!
You can also delete things in bulk by clicking on the three dot menu at the top of the timeline, choose "Delete activity by" and selecting a date range to erase on the next page. If you want an entirely blank slate, opt for the "All Time" option.
What if I want Google to stop tracking this sort of data?
You're in luck! You can "pause" Google's data collection whenever you want. To lock things down, head to myaccount.google.com/activitycontrols. From there, you can tell Google to stop saving information about things such as your searches, location history and YouTube watching habits.
But if looking back through your My Activity timeline has you a little paranoid, it's probably also worth running through Google's Privacy Checkup. That feature, which can be found at myaccount.google.com/privacycheckup, uses a simple interface to help you manage not only what data is being saved by Google but also what information about you may be public through services like Google+.
Is there a downside to erasing my history — or pausing Google from saving it altogether?
Well, there's definitely one for Google: The search giant makes the vast majority of its money from distributing targeting ads, which is made easier by the trove of data that they have about users' online activities. But that means that limiting the data they save will probably result in you seeing ads that are less relevant to your interests. And beyond ads, Google uses the information to help personalize their products to users' preferences, which can mean a more convenient online experience. For instance, Google has said that letting it save your search history can mean that it returns results quicker and letting it hold on to location history can help it suggest better commute options in its Maps product. So really, it's a trade off.