The Internet has created a new global community where people share various details about themselves with people they hardly know (or don't know at all). This means that people nowadays are much more willing and eager to share every day and common details about themselves, where people of the old days would simply have said "It's none of their business".
Now you may wonder: "What is so wrong with sharing my favourite colour, or my birthday online?"
While it does seem harmless, consider the following. When creating a new account, many websites may ask you to create a security question. This question is then asked to you when you can't remember your password when logging in the next time. By being able to answer the security question, is like being able to provide your password.
Many times, the security questions are things like "What is your first pet's name?" or "What is your mother's maiden name?". Many websites lets you choose your own security question, but people tend to make it an easy question to which they are certain they will remember the answer to. The problem is... we tend to share these details on social networking sites (like Facebook or Twitter). That means someone who only knows us even a little bit, can answer our security questions!
What things should I not share?
Social engineering is when someone impersonates you on a website by giving your username and password which they got through monitoring your activities online. The following points will help you steer clear of becoming a victim of social engineering.
Don't share your house address online. Telling strangers where you live can be dangerous.
Don't put your cellphone number online. Only people who know you should have your number.
Be careful what you share online. Not all your "friends" online, are your "friends" offline.
Be careful who knows your birthday online. It is frequently used as a security question.
It seems obvious, but be careful to not make your password known. Don't type it into any box that says "password".
Be careful to put your original ideas online. Ideas can also be stolen; it's called Intellectual Theft.