Arduino functions for writing to the Serial Console

Arduino software provides 3 commands for writing values to the Serial Console.

takes 1 or 2 arguments. The first is the value to print. The second (optional)
argument depends on the type of the first argument: If the first argument is
an integer, then the second argument can be one of HEX, OCT, or BIN, so
that you can specify whether you want that integer is displayed in base 10 (the
default) or base 16, 8, or 2. If the first argument is a floating point number,
then the second argument is an integer that specifies the number of digits to
print after the decimal point.
Each time Serial.print is invoked, it displays a value immediately to the right
of the previous value in the Serial Console.
behaves exactly like Serial.print, except that it adds a “newline” after it
displays its argument, so that when it is finished, any subsequent call to
Serial.print or Serial.println will begin on the next line.
writes one or more byte values to the Serial Terminal, and then returns
the number of bytes actually written.

Both Serial.print() and Serial.println() can print any single value,
e.g., an int, a double, a char, or a text string.