Until now, Amazon's Kindle and Fire devices have lacked one important feature that sets them far behind their Android counterparts: porn. Wait, that's not true, there's tons of porn on Amazon, you can hardly look on the bookstore without seeing self-published Harlequin-style short stories. But if you want to browse a bunch of sites on the less savory side of the Internet on your Kindle Fire without leaving a trail, you're out of luck.
Until now. The latest update to Amazon's proprietary Silk browser adds a private browsing mode, which won't record any history, cookies, or searches when enabled. It's basically the same thing that's been in Chrome and other browsers for years. Hooray, porn! (Fine, fine - there are some perfectly legitimate privacy and data security concerns served by private browsers, and some of them have nothing to do with looking at naked people. Happy?) To engage private browsing mode, just tap the menu button and select the new option. On the Fire Phone, tap the Tabs button and then select "private browsing." Any files saved in private mode can be kept or discarded when exiting.
The Silk Browser update should be headed to all Kindle Fire tablets sold from 2012 forward (basically all of them except the original model) and the Fire Phone. Sync your device to Amazon's servers and it should download automatically.
Source: Amazon Silk blog