CH340G USB to Serial Adapter
Historically, the most popular USB to Serial Adapter is the one that is based on either FTDI FT232 chip or Profilic PL2303 chip. Due to its popularity, as usual the market is then flooded with cheaper counterfeit chips from China. To fight against these fake chips, both companies updated their official drivers such that it will stop working properly upon detecting the fake chip.
Of course the problem is then with the user. When buying an USB to Serial Adapter, it is difficult to identify whether the adapter is using original or fake chip especially if you buy it online except perhaps from its price ;-). There are ways to get around this but I prefer to use adapter based on totally different chip, that is CH340G chip.
CH340G and its driver is made in China, so the problem with FT232 & PL2303 will unlikely repeat again ;-). It is cheap and performs well. In fact, it is also used in most Chinese Arduino clone boards that have built-in USB to Serial Adapter.
CH340G USB to Serial Adapter comes with 6-pins header and a jumper. The jumper is needed to short-circuit VCC & +3V3 pins or VCC & +5V pins depends on what TTL voltage level is required on the serial TXD & RXD signal pins. For ESP8266 and Raspberry Pi GPIO which uses 3.3V, you needs to connect VCC & 3V3 pins. The current available from the VCC pin is quite low that it is not enough to power ESP8266 like it is commonly configured on FTDI FT232 based adapter.
The official windows driver can be downloaded from this site. If you already have Arduino IDE installed and you are using Chinese clone of Arduino board, most likely you already have the driver installed.
The linux driver is also available from the same site. However for Ubuntu, I notice the driver is already in the kernel so you don’t need to install it.