The tablet_light segment starts with the earliest iPads and Android tablets. It contains tablet OS' like the Android 2.3-4.1 and iOS 3-8. Anything falling below the tablet_light specifications will be indexed as mobile.
These devices started entering the market in 2009 with a wide range of new features - but not without quirks. As an example position:fixed is supported in iOS 5, but has an incredibly bad update performance, making it virtually useless. Similarly Android 2.3 has a white-space error, requiring grids to always be less than 100% in total to avoid line breaks due to overflow.
Tablet are defined by a display size larger than 6". However this is more of a guideline, than a strict rule. There are some phones out there, that are more than 6" but where resolution, performance or even assumed user expectation, clearly makes them a phone. Those devices are indexed as phones, despite their large screen.
The reason why the minumum width is only 600px is because Samsung released a series of tablets with a 600px resolution in portrait mode.
As of December 2017 this segment represents ~20% of the tablet browsers and ~1% of all browsers (across all device types).
The tablet_light segment is defined by the following criteria:
- Primary input method is touchscreen
- Browser supports the tablet_light segment requirements
- Screen width of a minimum of 600 pixels
- Screen is more than 6 inches
The tablet_light segment supports the following features:
- CSS Transforms
- CSS Transitions
- CSS Animations
- Offline storage
Check out the complete feature support on caniuse.com.