QQ, MSN, GTalk, Skype, which is the most secure, which is the least secure?
A: Because of well-known reasons, the most unreliable is of course QQ, so if you have secrets or pornographic photos, do not pass through QQ. MSN communications are unencrypted in plain text and are not very reliable, but there seem to be plugins that provide encryption but require both parties to install it. Skype is a little more complicated. Simply put, don't use the simplified Chinese version of Skype downloaded from skype.tom.com, Skype's domestic partner. It's hard to say why, but please do your own search if you're interested (hint: The study was conducted by a lab at the University of Toronto, Canada). Please take a detour outside the wall to download the official Skype client. (For example, use this address to access Skype UK.)
GTalk is actually better, Google's own client provides encryption, but not many people use it, and there is no official client on non-Windows platforms. One thing to note is that, as far as we know, only the English version of the GTalk client has confirmed encryption. In addition, using GTalk through Gmail's web interface is encrypted with HTTPS by default.