Using a # at the start of a line (without the ! of a shebang) turns the line into a comment.
# This is a comment, to remind me of what follows!
Alternatively, the HEREDOC / HERE DOCUMENT notation <<IDENTIFIER can be used to create comments over multiple lines and is terminated by stating the same IDENTIFIER without the <<
# The shell will ignore this comment
echo "Example of a block of comment lines:"
A bunch of text
can now be created
over multiple lines
echo "Notice how the commented heredoc section is ignored."
Example of a block of comment lines:
Notice how the commented heredoc section is ignored.