ADB and fastboot commands

ADB
Android Debug Bridge (adb) is a versatile command line tool that lets you communicate with an emulator instance or connected Android-powered device.

Here are few useful adb and fastboot commands:

ADB:
adb devices - lists the connected android devices with their serial
adb reboot - Reboots the android into system
adb reboot recovery - Reboots the android into recovery
adb reboot download - Reboots the android into download mode to flash it via pc
adb reboot fastboot - Reboots the android into fastboot mode
adb reboot bootloader - Reboots the android into bootloader

adb install <path_to_apk>
adb pull <remote> <local>
adb push <local> <remote>

Fastboot:
fastboot boot <image.img> - temporarily copies the image into memory and boots up by that code
fastboot flash <sector> <image.img> - flashes permanently the image to the specified sector
fastboot flash <flashablefile.zip> - flashes the zip file of the entire system (ROM file)

source:
http://developer.android.com/tools/help/adb.html
http://techbeasts.com/2014/01/05/useful-adb-and-fastboot-commands-and-how-to-them/