Office 365 is essentially Microsoft’s answer to Google Aps, only different. You have many choices when it comes to 365, completely web based, web and computer applications, and then there is the available options, including mail, Lync, etc.
What is really nice about Office 365 is your information, documents, presentations etc. follow you. You can save everything to the cloud and have access from anywhere there is an internet connection. The integration between the many Microsoft services including SharePoint, Lync, Skype and Office is pretty incredible and useful for both businesses and consumers.