An Ultrabook is a sort of sub notebook developed by Intel. Ultrabooks are basically designed to reduce size and weight without compromising of performance and battery life. Intel announced the Ultrabook concept in 2011. The company has set aside a $300 million fund to be spent over the next three to four years in areas related to Ultrabooks.

The main motive of Intel Ultrabooks is to provide users thin, light weight, adaptive notebooks that offers excellent battery life and to improve power consumption of its chips for Ultrabooks, like Ivy Bridge processors, which will feature 17W default thermal design power.
In this race of technology ASUS had now launched its Ultrabook with the name Zenbook(UX21,UX31). The chairman of Asus Jonney Smith claimed these Ultrabooks have a battery backup of more than 7 hours, works on Intel second generation Intel core i7 processors and the highlighting feature of just 2 second resume time.
Asus Ultrabooks proved to be a strong competitor for Mac book-Air which takes 6 second resume time.
Model UX21 will be in market with the price of 999$ where as model UX31 will be launched with the price of 1,099$. The Acer Aspire S3′s is the lowest price selling Ultrabook with a price tag of 900$. The main difference between these two editions is mainly of display size the Zenbook UX21 featuring a small screen of just 11.6″ while the Zenbook UX31 is with the display size of 13.3″. The UX21 base model uses a Core i5 processor, 4GB of memory, and 128GB of SSD storage, but you can upgrade to a Core i7 processor. Moreover Zenbook UX31 has a storage capacity of 256GB SSD and starts $200 less than the Mac book -Air.

A very innovative feature added by Asus to its Ultrabooks is an instant backup of data as soon as battery level reaches to 5 percent. Now you do not have to worry of losing your data while working on low battery level. In addition to these exiting features it includes the resolution display of 1600×900 pixels which is quite highlighting and better feature comparatively to Aspire S3′s which has a resolution display of 1366×768 pixels and Mac book-Air having 1440×900 pixels resolution. The Asus Ultrabooks satisfy important requirements as the Zenbook UX31 is merely 9mm thick at its largest point and weighs less than 3 pounds. Considering its ultra thin feature and body which is made up of aluminum sheets some may be wondering how this machine remains cool without transferring heat on to the lap of a user. There are several well placed ventilation holes at the back edge whose sole purpose is to efficiently allow cool air into the chassis while directing heat away from areas touching your skin.

Few other features includes-
- Processor speed-1.6 GHz
- Memory-4GB
- Size-17x297x196mm
- USB ports-2
- Operating system-Windows 7 Home Premium 64-bit
- Graphic memory-384MB