ESP8266 UART with Arduino UNO

[ktauchathuranga]

can i directly communicate with ESP8266 and UNO?
my friend did that and it works!
and also i saw some peoples saying i have to use logic converter.
what should i do?
why my friends circuit works?

[ESP_Sprite]

You should use a logic converter, yes, as officially the ESP8266 pins are not 5V compatible. In practice, they seem to tolerate 5V for at least a limited amount of time, so that's why your friend gets away with not using them, but we do not advise it as we don't know if that keeps working forever, over the entire temperature range and for any batch of ESP8266 chips.

[bidrohini]

Yes. As ESP-Sprite has already said, you'll need a logic level converter. Here are some tutorials and write-ups that will give you a clearer idea:
https://randomnerdtutorials.com/sending ... ia-serial/
https://www.theengineeringprojects.com/ ... ation.html