Team Development for Sitecore (TDS) brings all of your Sitecore objects into Visual Studio. Imagine having all the benefits of a Source Control Management System fully integrated into your Sitecore Development environment. Team Development for Sitecore (TDS) makes that a reality. Now you are able to take advantage of the value Visual Studio Team System (VSTS), Subversion, or many other Source Code Management Systems offer to you on your Sitecore-based projects.
You could build and deploy
your Sitecore projects
Without
Team Development for Sitecore
Build your code from your Source Control System
Copy the code to your target environment
Tell the development team that you want to do a deployment so they can create packages of all their changes
Hope that you got everything and start deploying 1 or more packages to your target environment
You could build and deploy your Sitecore projects
WITH
Team Development for Sitecore
Continuous Integration automatically moves your code and Sitecore items to your target environment from your Source Code Control System.
Using Continuous Integration all code and Sitecore items are deployed to the target server automatically. Maximum number of user steps 0.
If you choose to not use Continuous Integration (Production deployment, for example) you can let Team Development for Sitecore create an Update Package for you. Maximum number of user steps 1.