In March last year, the Office 365 team announced significant updates to SharePoint Online limit increase. These announcements were related to SharePoint Online offering a site collection limit of 1TB, which allows the people working on it to store more in a single location. The second announcement was related to storage scale in the Cloud being made unlimited. Most of the SharePoint Online Administrators are not aware or are not using these new features that were extended to the SharePoint Online users.
If SharePoint Online Administrators wants to learn more about site collection, top-level or root site of a web application. Site collection can be created to host sites that will have something in common. Site collection is a way to organize sites for a common purpose. With the course available on Microsoft Virtual Academy, you can learn about types of site collections, what are the considerations while creating them, creating Central Administration and using PowerShell and how to manage them in SharePoint 2013.
Storage Options – what was the update?
Private and Public site collections are managed with the SharePoint Online admin center. Your SharePoint Online admin can assign the required storage to the selected site collection. The allocation can be done in an incremental manner like 50 GB, 100 GB, 250 GB, 500 GB and 1024 GB. The default storage is set at 250 GB for a user for every allocation.
There are an increasing number of Office 365 and SharePoint users and this is the reason to increase unlimited storage scale. This is expected to take care of current and future storage needs. The default OneDrive for Business storage is 25 GB, 50 GB for e-mail storage, and 5 GB for site mailbox and total tenant storage (available for all Office 365 business customers at 10 GB in addition to 500 MB times the number of users). For growing storage requirements in different work streams and content types, Office 365 provides a lot of storage space. There is a provision to buy unlimited extra storage from SharePoint Online admin center at the rate of per GB per month.
 Source: blogs.office.com/2014/03/14/sharepoint-online-announces-1tb-site-collections-and-unlimited-tenant-storage-scale
By: Meenakshi Vashisht