Google launched the Gmail service on April 1, 2004 on invite basis. In these eight years time span, it has gradually increased its storage from 1 GB to 7.5 GB. Google has launched the Google Drive, cloud storage service yesterday and to celebrate it, the company has added 2.5 GB storage for the Gmail users.
The Gmail team has mentioned in the official Gmail blog that they are increasing the free storage from 7.5 GB to 10 GB. This does not mean that the Gmail storage counter will jump directly to 10 GB. It will happen gradually. This storage is not fixed and it will be increasing slowly.
This additional 2.5 GB increase is for all the users of Gmail while those who are signing into the paid account of Google Drive will get a total of 25 GB free storage. The paid accounts enable them to enjoy storage space of 25 GB, 100 GB and 1 TB in Google Drive for $2.49, $4.99 and $4.99 per month.