The shaitan (evil) can deceive people anytime so we should be alert...Is chatting on the web permissible, what are its harms?
Otherwise talking on a different way which brings minds wrong thoughts and feelings is not permissible, since such things astray people to wrong results.
Also, the essence of a family should base on a sure ground to be able to start and constitute a strong family.
Therefore, as Islam advices parts to an arranged marriage, it considers their seeing each other as an essence as well.
But relations such as flirt are not permissible even if one of their relative is with them.
As our religion prohibits and forbids adultery, it also prohibits and blocks off the ways which lead people to adultery.
Similarly, chatting and having small talks with the person you met on the internet is not permissible.
But if the aim is to convey and to endear Islam, this is out of matter.
But if the conversation reminds us about sacred subjects, Allah, death, afterlife and religious life; of course it is not prohibited besides is a good deed. If you act in accordance with such rules then we can say that you are not committing sins and you are able to protect yourself.
Also we recommend you to act in accordance with your conscience.