So you have a phone, and it’s great. And you take the best pictures. Amazing! Photos are so much fun to take, and look at, and share. However, knowing where all your photos are stored, how to delete them, and how to keep them safe is much harder.

It’s possible you’ve taken a bad selfie, or an embarrassing selfie, or a photo you thought you’d share, but decided against. How can you be sure that those photos are really, truly deleted?

We asked some of Thorn’s engineers to boil down photo security for you. And it comes down to 3 things. Know where to permanently delete your photos, know which apps can access your photos, and always use strong passwords to keep your photos safe.

What happens when I delete a photo or video from my iPhone?

There are several possibilities:

If you have iCloud Photo Library enabled, deleted photos are placed in the “Recently Deleted” album (both on your phone and in iCloud), where they remain for 30 days. After that, they are permanently deleted from both your phone and your iCloud account. To delete photos before the 30-day time period is up, delete them from the “Recently Deleted” album.

If you do not have iCloud Photo Library enabled, the photo is available on your phone in the “Recently Deleted” album for 30 days. You can delete it permanently from that album. The photo will never be in iCloud Photo Library in this case.

If you have added a photo to your “My Photo Stream”, you will need to go to that photo stream and delete it from there.

Backups of your phone, either via iTunes or iCloud, may still include deleted photos. If you are using iTunes to backup your phone, we recommend enabling encrypted backups. If you are backing up via iCloud, encryption is enabled automatically (thanks Apple!) — however, anyone with your iCloud password could recover your iCloud backups and (potentially) your photos. So, keep your iCloud password safe!

In addition to the above, any apps that you have given permission to access your photos may have stored copies of your photos in the cloud. Two common apps that do this are Google Photos and Dropbox, but there are many others. If you use this type of app for photo management, be sure to delete the photo from that app as well (and review their data retention policy).

What happens when I delete a photo or video from my Android Phone?

This is more complicated, since different versions of Android use different photo services and carriers can include their own software with the phone. The most common option on new phones is Google Photos.

If you use Google Photos: your deleted photo will remain on your device and in the cloud in a trash folder for 60 days (by default) before being deleted. After that time period, the photo will be deleted from both your device and the cloud. Get more information.

If you have a Samsung phone, it’s possible that Samsung Cloud Sync is enabled. According to Samsung’s support page, deleting a photo from the Gallery app will also delete it from Samsung Cloud (although they don’t specify a retention period).

As with iPhone, other apps may have access to your photos and thus may be storing them in their own clouds. Think carefully before installing an app that can access your photos.

What makes for a strong password?

There is a lot of advice, of varying quality, regarding choosing a strong password. What it generally boils down to, though, is that the easier a password is for you to remember, the easier it is for a hacker to guess. Therefore, you should choose passwords that are difficult to memorize — passwords that are long, use lots of symbols, and aren’t based on words at all. You should also use a different password for every website or app, in order to limit the damage in case one of the services you used experiences a security breach.

But if you do all that, how can you possibly remember all those passwords? Well, unless you’re Sherlock Holmes, you can’t. But a password manager can! Password managers (we recommend 1Password or LastPass) can generate strong, unique passwords for every site you visit or app you install. They can also remember all these passwords for you — keeping those passwords safe by encrypting them with one strong password that you can memorize.

Are photos/videos on my phone discoverable if someone is nearby?

On iPhone: no. You would need to explicitly share a photo or video with someone, either via an app or the built-in AirDrop feature.

On Android: no. Samsung phones have a feature called “S Beam” that works similarly to AirDrop, but you would also need to explicitly share a photo or video with someone.

Note: apps that have permission to view your photos can essentially do anything they want with them, including share them with nearby phones. Again, think carefully before installing an app that can access your photos.