How do I add characters to strings?

You can add a character to an existing string by using the concatenation operator "+". Here is an example:

my_string = "Hello"
new_char = " World!"
my_string = my_string + new_char
print(my_string)

Output:

Hello World!

In this example, the "+" operator is used to concatenate the original string "Hello" with the new string " World!" and store the result back into the variable "my_string".