We will use the pyserial module to write a separate data gathering application in Python. For this to work, we'll have to shut down the Arduino IDE so that our Python program can access the USB serial port.
A serial interface will see a stream of individual bits that can be reassembled into bytes. The low-level sequence of signals flips between high and low voltage at a defined rate, called baud. In addition to the baud, there are a number of other parameters that define serial interface configuration.
In some contexts, we might summarize an interface configuration as 9600/8-N-1. This says that we will exchange bits at 9600 baud, using 8-bit bytes, no parity checking, and a single stop bit included after the data bits. 8-N-1 specification after the "/" is a widely-used default and can be safely assumed. The transmission speed of 9600 baud can't be assumed, and needs to be stated explicitly. Our Arduino Serial.begin(9600) in the setup() function specified...