Since you are communicating through a keyboard and not face to face, there is always the chance that the person you are conversing with online is not who he says he is.
You cannot guarantee that the photo he has put up is really of himself, or that he is as young or old as he claims. The Internet makes it very easy to lie or exaggerate truths to appear more appealing. With online dating, you cannot be positive that the person with whom you are speaking is really the person on the other side of that computer screen.
Such things as body language and tone of voice play an important part in developing chemistry between couples.
You cannot make a clear evaluation of these aspects through online dating. Let's face it, physical appearance matters as well. Now, even if you have seen pictures, you cannot always judge a person from these as many people appear different in real life than they do in their photos. Video calling is always an option, but this is still not the same as being in the same room as someone. You may find that you click with a person really well online, but that there is no real chemistry between you when you meet face to face.
Because online dating allows you to meet people from all over the world, you may find yourself falling in love with someone who lives in a different state or country than you.
Long-distance relationships are extremely difficult and hard to manage. This also poses the issue of relocation. You have to consider the possibility that if you pursue this type of relationship, you may end up having to pack up your things, give up your career and leave your friends and family behind to travel across the world just to be with this person.
While online dating can be fun, it also can have negative psychological impacts.
When you set up a profile on an online dating site, you get many responses and may end up chatting with a whole bunch of people as opposed to just one person. You may become so addicted to flirting and constantly moving on to new people due to the ease of online dating that you fail to develop any kind of serious relationship. Once you're stuck in this cycle, it will be very hard to drag yourself out.