Wikipedia:SAFE

Wikipedia can be a fun place, a stimulating forum, and an addictive hobby. It can also be a threat vector for safety, security, and privacy.

While most editors will not encounter any more than minor annoyances from people they disagree with, some people will become targets of harassment, or in extreme cases, violence or imprisonment.

The Wikimedia Foundation is very good at logging little private information and sharing even less with governments or authorities; however, you can still out yourself.

If you are unsafe

 * If you encounter harassing behavior on-wiki, contact an administrator privately, via email.
 * You can also privately reach out to the Arbitration Committee
 * You may choose to escalate to Wikimedia Foundation Trust and Safety by emailing ca@undefinedwikimedia.org.

If there is an active emergency, including a threat of harm to people or property, contact emergency@wikimedia.org. You should report it even if you think it's "not serious."

Advice
Here is what to watch out for.

Register an account
Register an account. When you edit logged-in, your IP address is hidden, meaning your geographic location is not disclosed.
 * Choose your username to minimize identifiable information. This could include your real name, or usernames you use on other websites. The safest option is to use a username you do not use anywhere else that does not contain identifying information about you.
 * Create a strong password that you do not use elsewhere.
 * Create a dedicated email account to be used for Wikipedia, not your everyday email account.
 * Always log in. Any time you forget to login, edits you make will be saved under your IP address.
 * Some people on-wiki qualify for two-factor authentication during login. You can request it.

Everything is public
Every page is public. There are no secret or hidden spaces to work, except offline.
 * Your personal pages are public too: user page, talk pages, sandbox pages are visible to everyone.
 * You can’t unpublish content. In extreme cases it can be hidden from public view, but you should assume that something posted has been seen by someone.
 * Be careful what you reveal early on. You never know when disclosure will become a risk.
 * People can follow your contributions. This is a normal part of the collaborative process, but can lead to harassment through wikihounding.
 * People can investigate you from what you edit. Editing about local towns, politicians, sports teams, schools, etc. can inadvertently reveal personal details about yourself.
 * You should expect public scrutiny of your work, as though you were a public figure.
 * If someone emails you, and you email back then they see your real email address.

Files reveal metadata and more
Files uploaded might have sensitive information such as geographic coordinates, contributor name, etc.
 * As an example, see the metadata for this file.
 * Photographs might have identifiable features that might show location.

Networks are not anonymous
Socializing online as a Wikipedian brings risks, unless your editor identity is entirely separate from your network identity.
 * Beware of your connected social media profiles and posts that reveal date of birth, friends, and employer.

Outside of Wikipedia (exists)
Real life events (meetups, edit-a-thons, Wikimania) can expose you to unknown individuals.
 * Journalists might reveal your identity if you tell them how long you've edited, favorite topics, etc.