Google has been adding more focus lately on Gmail by allowing more ways for users to customize their experience. This include undoing a sent mail (for those who have sent an email by mistake and want to retract it), trip bundles, adding a custom signature for a more personalized way in sending messages, opening an app directly from inbox, and notable improvements to Google Calendar on iPhone.

The latest update caters to those who want to have more theme options on their inbox. Apart from adding more artistic appeal, themes also play a huge role in keeping one's inbox more organized by being able to point out the difference between a home inbox and a work inbox. Google first introduced the theme option in 2008 and since then, it had become an important feature of Gmail.

"Your inbox is home to some of your most meaningful and entertaining messages - from that acceptance letter, to those throwback photos - so we think it's important for Gmail to feel just as personal (and fun!)," wrote Software Engineer Gaurav Vijay on the company's blog page. "That's why we offer lots of ways to customize your experience - from inbox categories, to email formatting, to shareable selfies - and why today we're expanding your options with additional themes, and emoji."

The new feature will include hundreds of new theme selections, with some having high-res options. Google said that some of the images are even captured by their own staff.

Just like before, users will still be able to upload their own images and use them as themes. This time, they can also do some editing such as adding a blur, vignette and even a text background to make things even more personalized.

Along with the new selection of themes, Gmail users will also be seeing new emojis in their inbox, such as a new set of smileys and other categories that include holidays, nature, food, etc. These emojis may look familiar as they've been available for quite some time now in Google Hangouts.

While the latest emoji upgrade may sound like a minor change, Google believes that it will absolutely revolutionize the way users communicate on their mobile devices. It has become apparent that more and more users are gearing towards mobile messaging where emojis have played a big role in message sending.

Furthermore, Gmail now has 900 million users, which is notably higher than the 425 million users noted in 2012. It is believed that 75 percent of these users access the service from their smartphones.

Google understands the increasing demand for customization from these users and has taken an important step to meet such by adding more support for new themes and emojis. The rollout has already started and will take a few more days for it to become fully available to all users.

"Check back soon if you don't see them yet. Once you do, definitely share your favorite themes and emoji with us on Google+, Twitter and Facebook," wrote Vijay.