Skype is a free VoIP application that also offers paid features. Instant messaging, audio conferencing, video-chatting, file-sharing and screen-sharing are among Skype's features. Paid features include cheap rates to telephone numbers with Skype credit, group video calls and group screen sharing. If you want to use Skype, you must create a free Skype Name. Skype works with most operating systems.
Having more than one chat account may have benefits, but few people would deny the potential convenience of being able to merge the accounts. Skype and iChat, for example, both offer instant messaging, audio-conferencing, video-chatting and screen-sharing. Being able to use them together would certainly make your life easier, but there are several reasons why you have to use these two applications separately.
Apple's iChat is the default instant messaging application used with the Mac OS X operating system. iChat offers features such as instant messaging, audio calls, video calls, screen-sharing and iChat Theater. iChat Theater lets you drag and drop images and movies directly into a chat window to share them. As of the time of publication, iChat is not available for other operating systems.
Skype accounts require a Skype Name and are independent from any other online service. Like Skype, iChat is free, but you must have an Apple ID or AOL Instant Messenger (AIM) account to use it. iChat is also compatible with Google Talk, but lists your Google contacts in a separate window and is not connected to your iChat and AIM accounts.
Because Skype and iChat are different applications that require different accounts, you cannot use one with the other. You can keep both open on your Mac at the same time, or search for your Skype contacts on iChat and vice versa, but they can't be merged. If you opt to leave both open on your Mac at the same time, keep in mind that you won't be able to simultaneously use your iSight webcam and microphone. If you're audio or video chatting in one, you'll only be able to instant message in the other.