Helping people with computers... one answer at a time.
Being harassed or bullied online is frighteningly common. While threats are rarely carried out by these cowards, it can still be very unsettling.
I met a boy in the chat room and talked to him decently and did not give him any of my personal information. After few days his behavior was not good and I stopped talking to him. He sent me email that was an invitation for speed dating. He once said to me in chat that this attitude will be costly for me in future. I am afraid. Can he harm me? Can he hack my computer to get my information? If yes, can he hack my all accounts or only that particular account which he knows?
Am I safe on my computer?
You're probably just as safe as you were before ever talking to this person.
But you're not alone in being concerned. I hear about your kind of situation all the time, and the bottom line question is always the same: "am I safe on my computer"?
The answer isn't really yes or no, I'm afraid. It depends on a lot of different things, which I'll review for you.
It's very easy to say things on the internet that you can't back up - things that you can't follow through on. Heck, there are those that would say that most of what you find on the internet is empty promises, threats and misinformation.
By far the majority of the threats made by people in chat or online in general are just that: empty threats; things that they never have any intention of actually doing, just things that they say to try and scare you. They say things because they can do it without fear of getting caught. In fact, these cyber-bullies are typically cowards since they would never say such things if they could be found out, or had to say them to you face-to-face.
However, that doesn't mean that they aren't scary since of course there is that tiny fraction of people that might say these kinds of things and actually mean it.
When it comes to social media, instant messaging and chat, there are no hard and fast rules about what the other person can or cannot find out about you - it depends on the specific situation.
It depends on how much information you may have given out and how much information about you is already "out there".
So let's look at what this person might have learned from you in chat:
Your name. It's unclear if you've used your real name in the chat room or not. If you used a fake name (which is always highly recommended), then this typically gives the bully nothing to go on - except if you continually use the same fake name over and over again with other services and on the internet in general. More on that in a moment.
If you've used your real name - especially your full name - then anything that's public information relating to your name is easily accessible to the bully. Depending on how common or uncommon your name is, this could make it as easy as opening a phone book to find you, especially if you've shared something else.
Your location. Even in general terms, your location is something that can quickly help narrow down someone's search for you. Again, it depends on how much other information you've inadvertently provided, and how uniquely identifying that information is. For example, in my case a unique last name like "Notenboom", and a general location like "Seattle" - even though I don't live in Seattle itself - is pretty darned unique, and could quickly be used to find out a lot about me.
You might think you never mentioned your location, but it's easy to give it by accident. If you said something like "I went to the so-and-so concert last night" it's very easy for someone to look up the concert schedule for "so-and-so" and know exactly where you were.
You might not give your location at all, but your computer might.
Your IP Address cannot be used to physically locate your specific computer, at least not without the police's help, so that's specifically is something you do not have to worry about. However, if the chat or IM software allows the bully to see your IP address (most do not), then depending on how that IP is identified publicly by your ISP, the bully might be able to use it to find out the city you're in. Or he may just be able to determine your country and nothing more.
For example, looking up my home IP address, depending on which service you use, it will tell you either Portland, Oregon (300 miles wrong) or Seattle (20 miles wrong). The former doesn't help much, and in fact serves as a nice misdirection. The latter might help since coupled with other information as I mentioned above, it might allow a bully to narrow down his search.
Other things you said are often the biggest problem. It's embarrassingly easy to accidentally tell more about yourself than you realize when chatting. You might mention a school, or an event - like the concert I mentioned above. You might mention your age, or something that can be used to figure out how old you are. You might mention all sorts of little bits of information that by themselves mean nothing, but when taken together can tell someone a lot about you.
What you say in chat to this person isn't the only thing to be aware of. In fact, it's your entire online presence that a bully can then use to threaten or intimidate you.
For example, let's say you've used your real name, and the bully can figure out your general location from what you've said. Now that person can go find your Facebook profile, or MySpace profile, or just start doing Google searches for more information about you. Depending on how careful you've been with everything you've ever posted publicly, someone may or may not be able to find out a lot about you.
That's really the bottom line here: it all really depends on what information you've given someone, and what other information is available about you online. If you take simple steps to never reveal anything remotely personal about yourself then you're probably quite safe.
I also don't want to alarm you - as I said, by far the most common situation is that the bully is just that - a coward who's hiding behind internet anonymity himself so that he can say things to upset and scare you, and nothing more.
I do want to also address that one other question you had: "Can he hack my computer to get my information?"
The answer is that we're all under attack every day. Hackers and malware authors are trying to hijack your computer via all sorts of means in order to infect you, hack your accounts, send spam and God only knows what else.
You need to be protecting yourself from those attacks already. Having good passwords and never ever sharing them, having good security software and hardware like a firewall and anti-malware tools and the like, keeping your private information private, knowing not to open attachments, click on links in email and understanding what things like phishing are are all important steps you need to take anyway to keep your computer safe.
Your bully's likely no worse. Even if you hand him your IP address and email address, he's no match for the security you should already have in place.
It is very possible to chat and do other things online safely. Millions of people do every day; it's a fun and important way to connect.
But you must take responsibility for that 'safety' part.
And that'll do more than anything else to keep the bully's empty threats just that - empty.