ESP is working on 3,3V so we must use an external regulator in order for it to work. Using Arduino Uno is one of the options. It will work, but it might be unstable since ESP can get to about 300mA of current when it is in transmitting mode.
ESP8266 has a two working mode: Programming and Working.
In programming mode, we flash firmware to ESP. To enter this mode, you must first connect GPIO0 to LOW when ESP is not connected to power supply. After connecting everything, turn power supply on.
Working mode is the mode in which ESP8266 module is working and running firmware. To enter this mode, you must connect GPIO0 to floating (meaning that the module is not connected to anything). As in case with the Programming mode, you must first reset the module (put it off and back on to power supply).
To install the firmware, we use a FTDI.
ESP can be use as Arduino because we have it in ARDUINO IDE, but we will talk more about this in the next tutorial.