Private data

What Are “Private Data”?

Private data is information that relates to an identifiable person—either directly or indirectly. What matters is not only whether a piece of information is unique, but also whether a person can be identified by combining multiple pieces of information.

Typical examples of private data include:

Identification Data

First and last name (especially together with additional contextual information)
Date of birth, age, marital status
ID/passport numbers (e.g., identity card number, passport number—never post these)
Signature, biometric data (e.g., facial images, unique physical characteristics)

Contact Information

Phone number, email address
Home address, exact postal address, location information
Clues such as “I live on Street X” or “I live next to School Y”

Account and Access Data

Passwords, TANs, security codes
Screenshots of banking apps, invoices, or other apps
Account/IBAN information (even partial information should not be made public)

Financial and Contractual Data

Salary information, bank statements, tax documents
Credit card or PayPal details
Invoices containing customer numbers/order numbers

Location and Everyday-Life Data

Real-time location (e.g., a live story saying, “I’m currently on vacation in …”)
Photos showing recognizable house numbers, mailboxes, street signs, license plates
Routines: “I’m always at the gym on Tuesdays at 6 p.m.”

Media That Can Reveal Personal Information

Photos and videos showing surroundings that allow someone to trace your location (e.g., school, workplace, club facilities)
Metadata (EXIF) in images that may reveal the location/date of the recording
Before-and-after photos that may reveal building plans/floor plans

Social and Personal Information

Family matters, photos of children (with names or school information)
Health information (doctor’s appointments, diagnoses)
Employers, positions, departments—especially when combined with tasks/appointments

Risks: What Can Happen When Private Data Is Published?

The greatest risks usually arise not from posting a single piece of information, but from the combination of multiple clues and their permanent availability online.

Possible consequences:

Identity theft and fraud: Private data can be used to derive security questions, create profiles, or set up fake accounts.
Stalking and harassment: If someone knows where you are or how your daily routine is structured, the risk increases.
Burglary/theft (opportunistic): Visible absence (“On vacation now!”), precise location information, or regularly occurring times can increase the risk.
Social disadvantages: Employers, landlords, or schools may see information; false interpretations are also possible.
Doxxing/sharing by third parties: Even if you share only a small amount of information, other people may add to it or redistribute it.
Permanent ability to copy: Posts, images, and comments can be saved, shared, and archived—even if you delete them later.
Reputational damage: Content is often taken out of context or used for purposes beyond what you intended.
Legal and privacy issues: Depending on the content, legal risks may also arise (e.g., personal rights or data-protection issues involving third parties).

How Can You Best Protect Yourself?

Practical rule of thumb: Sharing less is better than trying to judge whether something is “probably okay.”

1. Maintain Anonymity Consciously

Anonymity does not necessarily mean having “no name at all.” Above all, it means not providing information that makes you easily identifiable or creates a link to real people or places.

Use privacy settings (e.g., “friends only,” restricted profile visibility).
Avoid “live” posts containing real-time location information.
If appropriate, do not use your real name, or clearly separate your professional and private identities where possible.
Protect family members in particular: children, partners, and parents may be especially vulnerable.

Why this matters: The better your anonymity, the harder it is for strangers to combine individual pieces of information into a complete “profile” about you.

2. Do Not Share Private Data With Strangers

Strangers online are difficult to assess. Even if someone “seems nice,” remember:

You never know who is actually behind the profile.
You do not know where your data may end up.
You cannot control whether others take screenshots or aggregate information.

Therefore: Do not share personal contact details, your address, or precise location and routine information with people you do not know personally and reliably.

3. Check How “Confidential” Information Is Really Being Treated

Before uploading something, it is worth doing a quick check:

A) Check Social Media Settings

Who can see it? (Public / Friends / Custom)
Can people search for your profile?
Can strangers see your posts, photos, or stories?
Is location data automatically shared?

B) Pay Attention to Photos/Posts

Are license plates, house numbers, addresses, signs, school names, or company names visible?
Do images contain metadata/EXIF (date/time/location)?

C) Check Websites

Look for information about how data is processed.
Is there a privacy policy?
Is personal data stored, shared, or used for advertising?
Is there information about tracking (cookies, social media plugins)?
Reputable websites explain transparently what they collect. Unclear websites are a warning sign.
Is there information about encryption of data on the website?

Practical tip: If you are unsure, assume that your data is not completely confidential.

Which Types of Data Should Be Especially Protected?

These categories are “no-go” areas for public posts:

Identification, Account, and Access Data

ID/passport numbers, IBANs, credit card information, passwords, TANs, QR codes from invoices

Exact Address and Whereabouts

Home address, exact parking/storage locations, frequently used routes, clearly identifiable periods of absence

License Plates and Unique Location Markers

Vehicle license plates, house numbers, mailboxes, door signs

Health Data

Medical appointments, diagnoses, treatments (including indirectly identifiable information)

Data About Children and Family Members

Name + school + photos + age/grade = particularly risky

Documents & Screenshots

Invoices, contracts, performance records, application documents

Simple “Everyday Rules” for Social Media

Pause for 10 seconds before posting: “Could someone use this information to plan around my daily routine?”
Keep location information vague: Instead of an exact address, say “visiting somewhere near …”
Check faces/surroundings: Blur or hide important details.
Do not post live or in real time: Posting later reduces the risk.
Control who can comment and share: Approval settings and moderation can help.
Minimize data: A nice photo without unnecessary contextual details is often better.
Remove metadata: “Clean” images before sharing them, depending on your device/platform.

Quick Checklist: “Before I Post—What Private Data Is Still Included?”

1. Can I or my daily routine be identified?

No combination that clearly identifies me (name + location + club/workplace/appointment)
No real-time routines or recurring patterns (e.g., “every Tuesday at 6 p.m.”)

2. Have I Checked the Location & Surroundings?

No exact address / house number / mailbox
No live location (“I’m there right now”)
No recognizable signs/street signs/school names/employers
No license plates (not even partially visible)

3. Have I Anonymized Personal Content in Photos/Videos?

No photos of children showing their names/school/group
Faces only when genuinely necessary and consent has been given
Background details (doors, mail, calendars, screens) blurred or hidden

4. Accounts, Documents, Sensitive Data? (No-Go)

No ID/passport numbers, no signatures
No bank/account/IBAN information, no TANs/QR codes
No invoices/contracts/screenshots containing customer numbers or amounts

5. Have I Checked the Platform/Website’s Privacy Practices?

Set visibility to “Friends/Private” instead of “Public”
Disable location sharing (if active)
Advertising/tracking plugins and data transfers on the website are plausibly explained in the privacy notice

Quick Decision Question: Can Someone Use This Information to Figure Out My Routine, Where I Live, or Who I Am?

If yes → better not to post it, or anonymize/cover the relevant information first.

Conclusion

Being cautious with private data is not paranoia—it is security awareness. Private information may seem harmless on its own, but when combined with other clues, it can become a risk. Maintain your anonymity, do not share sensitive data with strangers, check your privacy settings and how websites handle data—and protect identification/account information, exact locations, and health and family information in particular.