An apostrophe starts a comment that runs to the end of the line. Comments explain why the code does something; the code itself shows what.

Code

' This line is a comment

• Explain intent

  ' Rates are quarterly, so divide by 4 → Explains an otherwise puzzling division

  The why, not the what.

• Trailing comment

  total = total + x ' running sum → A comment after code on the same line

  Short trailing notes.

• Comment out a block

  Select the lines, Edit toolbar > Comment Block → Every selected line gets an apostrophe

  Disable code temporarily.

• Put a header comment on each procedure: purpose, inputs, and date.
• The Edit toolbar (View > Toolbars) has Comment and Uncomment Block buttons.
• Rem also starts a comment but nobody uses it.

• Commented-out code left for months confuses everyone; delete it.
• An apostrophe inside a string is not a comment, but one after a string is.