How to Unlock and Root the Nexus 7

The Nexus 7 is a powerful device. Though it has received significant attention, many Android users might not know its real power when it's unencumbered by carriers. To release its power, you have to root it, which will make it more useful.
This post is teaching you how to unlock Bootloader and root Nexus 7 in detailed steps. To root Nexus 7 is with no difficulty attached in principle—unlock the bootloader, use fasboot to root TWRP Recovery, followed by TWRP rooting SuperSU.zip by which finally root Nexus7 on Android 4.3. This is the general procedure and the following will show you the steps in detail.
Please note that rooting has risk involved. Here we are not held liable for any damage to your device due to the instructions you follow.

Before you start, please make sure that fastboot driver is installed, if not, please follow the instructions below.
Please note that the unlocking will erase all data, so please make a full backup before that. (Or you can recover data from Android with some third-part software)

Unlock Nexus 7 Bootloader
1. Install Android SDK (http://developer.android.com/sdk/index.html). In fact, you only need fastboot.exe and adb.exe (download from here), and place them in specific location. Here we put them in C:/adb (built adb directory under the root directory of disc C);
2. Install Google USB driver (http://developer.android.com/sdk/win-usb.html);
3. Turn on USB Debugging on Nexus 7;
4. Open a command prompt and enter C:/adb (where you had placed the fastboot.exe and adb.exe);
5. Input the following command: adb reboot bootloader;
6. Once n 7 2 had entered into bootloader mode, input this command in command prompt: fastboot oem unlock;
7. Use the volume button "+" on n7 to select "Yes" and confirm it by power button;
8. When the n7 screen says Unlocked, select "Start" by the volume button and confirm it by power button.
Once these steps are done, the bootloader is unlocked. Next, let's begin the rooting of Nexus 7 2.

Root TWRP Recovery and then root N7
1. Download SuperSU. The latest version is 1.4.5, the follow-up can be updated by play store:http://download.chainfire.eu/343/SuperSU/UPDATE-SuperSU-v1.45.zip
2. Place SuperSU under the system root of n7;
3. Download TWRP recovery.img file to C：/adb (the directory where you placed fastboot.exe and adb.exe by which the needed commands is completed) (a crucial step);
TWRP Download：http://techerrata.com/browse/twrp2/flo
4. Make sure that your n7 is connected with computer and has entered bootloader mode, if not, please repeat step 4 and step 5 in the above unlocking toturial.
5. Launch a command prompt and input：fastboot flash recovery "recovery.img" （replacing "recovery.img" with the actual name of the recovery file）；
6. Once the rooting of TWRP is completed, the interface is still in Bootloader mode, please use volume down button to find out Recovery Mode and press power button to confirm;
7. Next, follow the steps below:
a：Install
b：Enter Select Zip to install
c：Find the SuperSU zip file you saved and select it
d：Select yes and root SuperSU
8. Post rooting, reboot the device.

That's it. That's rooting, which you may have heard a hundred times before but never do it. If you've got one, you may take a risk to have a try. Rooting the Nexus 7 is really easy. Or now you may have unlocked the bootloader and root your Nexus 7. Enjoy!