Teamspeak was founded in 2001, it’s a Voip software designed for gamers who often need to comunicate with each others during a game session.
The Teamspeak (TS3) software allows you to communicate with other users, but, unlike Skype, it has several additional features as it gives you the ability to create virtual rooms in which you can enter and exit freely, talk, chat with other people, send and receive media files, and so on.
Source Wikipedia
The target audience for TeamSpeak is gamers, who can use the software to communicate with other players on the same team of a multiplayer game. Communicating by voice gives a competitive advantage by enabling players to keep their hands on the controls.
How to get the software?
Visit the Teamspeak official download page to get the latest version of the client that works with your operating system (Linux, Windows, Android, IOS, ..), TeamSpeak is completely freeware, so you don’t need to pay for a license.
After downloading the Teamspeak 3finished, run the executable and follow the installation instructions.
Assuming that you are using Windows, in the next part we will see how to connect to a server.
Connect to a TeamSpeak Server
Click on the shortcut icon:

When you start Teamspeak 3 you get the following window:

ts3) main window
After clicking on Connect (Ctrl+S for shortcut) a small tab will open, enter the Server Nickname or Address, Server Password, Nickname and finally click on Connect to gain access to TS3.

Connection configuration tab
Once you are in you will get full access to your server, from there you can administrate it.
Add a server to the bookmarks
In the main window click on bookmarks and choose Add to Bookmarks:

Now you need to fill all requested informations that suits your needs:

Add new identies to your server
Click Tools on toolbar and choose identities or press Ctrl+I:

Afterwards you need to insert the Identity Name and Nickname:

Final Thoughts
TeamSpeak 3 is perfect if you are a gamer as it allows you to schedule events daily or weekly, reminding you to take part in a game or get in touch with your gaming friends.
It allows you to create real IRC style channels, with operators and moderators , administering everything through the client software or via the web interface by installing additional plugins (developed by third parties) on the server side.