The internet is not your laundry basket

Unlike other articles, the title pretty much is self-explanatory: the internet is not your laundry basket, so don't try to air your dirty laundry in it.

This is a common mistake made by people who think it's a friendly place hoping individuals may offer insight into their personal problems or can help out, however, a lot of hostile people (who may prefer to remain silent until they have some decent ammunition on you) will also exploit this information negatively.

There are psychological, financial and other reasons that this occurs.

Explanation
Besides numerous reasons not to air your own personal experiences (including privacy, safety and health), the main one is that hostile individuals will generally exploit any publicly aired dirty laundry as a means of provocation, manipulation and general attack. For people in general, it's seen as a means of revenge (especially given their anonymity offers protection against reprisals), for corporations it's a means of silencing a corporate dissent, for intel it's a means of discrediting an opponent.

Yearning of attention:
Unfortunately, not everyone gets attention in equal amounts, and humans, as social creatures, have a yearning to be heard. People are perhaps familiar with the term 'attention seeker' in one way or another, and an eagerness to air personal experiences is an example of that attention seeking behaviour (that is to say, it's natural). Unfortunately, in our eagerness to be heard, we will often publicly (on the internet) discuss things we often wouldn't mention in the open public. The yearning for attention is a symptom of a much bigger problem and airing personal problems on the internet is not the best way to address this (see below).

Schadenfreude:
Some people derive a sense of reward from schadenfreude, in that causing other people harm derives them a sense of reward. This may often be due to their own personal experiences, however they will often exploit an opportunity to do so if it presents itself, and airing any personal experiences presents a vector of exploitation and accusation sufficient for them to levy themselves upon you (especially if the individual suffers from an inferiority complex): by pulling you down they feel better.

Jealousy:
Another reason individuals feel compelled to exploit presented opportunities is jealousy, which is known as tall poppy syndrome, of which an individual attacks because they see someone with something they haven't. This isn't helped by the fact that statements can be presented or misrepresented in a manner akin to bragging.

Sleighted behaviour:
Individuals who feel sleighted will often feel threatened, and thus as part of natural threat-assessment behaviour, will attempt to dig up the past history of the individual they feel sleighted them (this can and does overlap with both schadenfreude and jealousy). It's a form of 'social justice' (note: social justice isn't necessarily 'just' or 'fair') in the wronged individual feels they are somehow 'evening the score'. However, individuals can bear grudges for a long-time, even long after the incident has occurred, especially if entrenchment has happened.

Discrediting/Poisoning the well tactics:
The final, and most dangerous reason (if anyone has been on the receiving end of corporate, government or similar kinds of harassment) is discrediting tactics, in which the personal history of an individual is dug up in order to embarass, discredit, provoke, harass, humiliate, shame, alienation, exploit, blackmail or otherwise threaten and manipulate an individual.

This is the most dangerous in that most agencies have fairly unlimited resources in digging up information on past histories, other family members, friends, etc, however putting the information out into the public domain of the internet makes this task even easier (and may give them leads to places they may have overlooked).

This is primarily so the individual (be they a whistleblower, informant etc) seems less reliable and more socially isolated from their peers, especially if incriminating behaviour (socially frowned upon behaviour, previous criminal behaviour, etc) is dug up and exposed.

In these instances different groups have different resource amounts, and it shouldn't be seen as 'oh, they'll have my information anyway' (they probably have a lot of people's information and thus suffer from information overload and thus cannot properly sift it all) but 'if they want the information they're gunna have to work at it'.

Some agencies have budgetry constraints on targets, and if it takes them a lot of money and resources to investigate a single background incident they're not sure exists, they're less likely to get approval for it than if you post up the incident publicly.

Defence:
There are numerous ways to go about protecting yourself from such harassment:

People are generally not geared to help out psychologically:
Contrary to popular belief, when people are in larger numbers, they are less likely to help out with a personal problem than if you spoke with them in person. This is known as the bystander effect in that the more people who are watching you in an attack, the less likely they are to help out, which is verified by the Milgram experiment in that the further away/less personal the authority figure is, the less likely someone is to respond (that is to say, a person is more likely to help you if you asked them in person than if you asked them on a forum).

So presenting personal problems on a forum is less likely to get help, so it's a good idea to do research for alternatives.

If you won't shout it in public, don't shout it on a forum:
To put it differently: if you won't tell a person something in person, don't tell it in public on an internet forum. A lot of people feel the internet is somehow impersonal and thus, as an expansion of the bystander effect, are also more likely to attack as they feel less personal connection with the victim. People are also conditioned to blame the victims in abuse as part of the 'just-world fallacy', primarily as a mental self-defence mechanism as victim abuse can be difficult to accept and tolerate (and it seems easier to a person if they 'justify' it by saying the victim was somehow, even partially, responsible).

Blaming the victim is not correct (victims, as part of their conditioning from their abusers, may repeat that they somehow deserved it, even though they didn't) and should not be tolerated in the public domain, however it's best to avoid such attacks in the first place if possible.

If you must post, anonymise yourself and the data:
For example, instead of posting it under your own name or own account, consider posting it under another account not associated with you. Change the format of the writings so it's not easy to identify who it's from (so remove names, dates and times if possible, and use short-hand, so instead of 'Mrs Anderson', put 'Mrs A').

If you're dealing with corporate or intel harassment, you will have to go several steps further to increase the odds of not associating it with yourself (ideally you shouldn't post it at all in these circumstances): use a public computer or a computer not associated with immediate family or immediate friends, use a throwaway account (never re-use it so an association cannot be formed), make use of things like 10-minute mail so there's no association to your email account when registering the throwaway account, do not use cryptonames/pseudonames or references that could implicitly be associated with you (random name generators can be found online, or you could thoughtfully mash your keyboard keys). Avoid the mistake of replying on the poster's behalf (which might clue perceptive individuals in it's from you).

Some forums and places can identify you by your operating system, screen resolution size and browser (as well as other statistics including which version of the OS you're using), so you may wish to make use of VMs (virtual machines) such as Oracle virtualbox coupled with Linux live ISOs (ISOs are the format that CDs are found in) to hide yourself as another operating system and browser. Some VMs can be made to run from pendrives on public computers (meaning you leave little, if any, trail on the public computer).

Make use of either proxy sites or VPNs to hide your IP (even if you're on a public computer or a computer that is not yours, it's a good idea to do your best to obsfucate the information). Sometimes proxy sites do not work with forums and it's a matter of trying different proxies until you find one that works with the forum of choice.

Beware of subtle clues in your writing known as 'signature writing', such as using British versus American spelling, Yorkshire slang versus New York slang etc. If you're terrible at spelling, try to spell correctly, if you're good at spelling, take a slightly lax approach at your spelling for a short while (can be easier said than done in both cases as it's habitual). If you use emoticons, drop them; if you don't use emoticons, use them more often. Change up your writing style.

If the information is associated to you and you start to get harassed...
Don't react, put on a 'pokerface'. With the exception of intel or highly paid corporation digging, it's hard for anyone to know for certain if you wrote it or not (unless you didn't anonymise it). Don't deny it (denial can be seen as confirmation in the eyes of the public especially if you do an overly specific denial, and most people do this naturally), don't acknowledge it, just ask why the individual keeps trying to associate the event to you? Do enough to acknowledge their attempt (don't acknowledge the association), but not enough, so to make it seem like it's of no concern to you (people will use your reactions to confirm or deny an association).

Based on the information they pass up to you (feel free to ask them questions to verify or deny, beware false confirmation attacks though) try to figure out where the leak came from. For example, if they parrot on about IP, chances are an admin, mod or technically minded individual was the source of the leak. If they make a reference you told one specific 'friend', make a mental note to remove that 'friend' from your information list (or you may wish to feed them a selection of information to see if it leaks out again to confirm if they are the leaker).

See if you can find the source of the leaks and then close them down. Even if you don't immediately close the source of the leak, it's an active step in the right direction in helping to identify who is responsible. Do psychological tracing attacks to figure out who is responsible for the leaks if it helps.

If you feel yourself breaking down, getting stressed or otherwise freaking out...
Take a break from the computer (no matter how hetic the drama), go outside, speak to some genuine friends or family members (maybe not necessarily about the event in questions but as a cooldown period) and take some time out to calm yourself down. Part of the discrediting tactics rely on you getting so stressed you freak out and alienate yourself from others further, eventually causing you to blurt out something that you regret saying.

Deny them the opportunity, walk away, calm down, and return when you've sorted yourself out. It's a source of great irritation to trolls to see that you haven't cracked under pressure and by acting the better person, you become a source of disparity compared to the aggressive actions of other people.