Some important adb commands for android debugging

adb root       - To get root access on device, this will provide full permission to user
adb remount - Remounts /system partition on the device
adb push      - To push any file, into device file system.

e.g. adb push <local system path>\<filename> <path on device>/<filename>

adb pull:  To pull out file form the device

e.g. adb pull <path on device>/<filename> <local system path>\<filename>

adb shell       - To enter into device's command prompt, and to execute shell command for device.
adb install     - To install any apk file( application file)

 e.g adb install mytest.apk

adb uninstall  - To remove application
adb version   - To know the adb tool version
adb devices   - list of devices connected to adb
adb get-serialno - Prints serial number
adb start-server - Starts ADB server
adb kill-server   - Stops ADB deamon server
adb logcat         - Collects device Log