The good news is that hovering your mouse over just about anything in the Skype window will display a tool tip (a little one-sentence definition or status report).

However, I found that almost right away I needed a cheat sheet for the online status icons, those green or gray clouds beside each contact. If you have anything to add or change, please do.

 Online: the person can receive calls or chats. If you set your status to , you can receive calls/chats from other Skypers. Depending on your privacy settings, you can receive calls from anyone, from people in your contact list, or from people who you’ve authorized to see your online details. To set privacy settings, go to Tools ->Options->Privacy.

 SkypeMe: the person is in SkypeMe mode, which means that everyone on Skype knows he/she is available and interested in talking or chatting, including contacts they don’t know. If you set your status to SkypeMe, you are allowing calls and chats with other Skypers who can find you by searching the Skype directory. To turn SkypeMe mode ON or OFF, go to File –> Change Online Status (Windows) or Account -> Change Status (Mac OS X).

 Invisible: the person appears to you as  offline, which means you can’t call or chat with them. If you set your status to invisible, you will appear as  to everyone else. Use invisible if you want to be able to make your own calls or chats, but don’t want to receive them. You’ll also be able to see the online status of everyone else in your contact list, even though you’ll appear to them to be offline.

 Away: the person temporarily can’t be reached–out to lunch, away from computer, in a meeting or whatever. If you set your status to Away, you are still notified of incoming calls or chats. Skype automatically switches your online status to Away if you have been inactive for a certain number of minutes. Go to Tools ->Options ->General to change this setting.

 Not available: the person can’t be reached. Sounds a bit more long term than Away. If you set your status to Not Available, you are still notified of incoming calls or chats. Skype automatically switches your online status to Not Available if you have been inactive for a certain number of minutes. Go to Tools ->Options ->General to change this setting.

 Do not disturb: the person doesn’t want to be bugged. Calls or messages are queued for you to check later. If you set your status to Do Not Disturb, you won’t be notified of incoming calls or chats (no pop-ups or ringtones).

 Not sharing: the person does not give you permission to see if he/she is online, offline, away, and so on. It’s probably nothing personal. When adding the contact you may have decided not to request their details, or they may have dismissed your request. To ask again if they’d like to share details, right-click the contact name and select Request Contact Details.

 Offline: the person is not available through Skype. They may have set their status to offline or invisible, or they may have logged off. If you set your status to Offline, you can’t make or receive calls/chats with other Skypers. But, if you have a voicemail account, people can leave you messages. You can also call forward your calls when offline to another number (either a regular number or Skype name), and you can still make SkypeOut calls (calls to regular numbers). 

 Skypeout contact: a person with a regular landline/mobile number. Not a Skype number.