Const defines a named value that cannot change. Put settings like rates, sheet names, and column numbers at the top of a module so they are changed in one place.

Code

Const TAX_RATE As Double = 0.07

• A setting

  Const TAX_RATE As Double = 0.07 → A module-level rate used everywhere

  Change once.

• Sheet names

  Const SHEET_DATA As String = "Data" Worksheets(SHEET_DATA).Activate → A sheet name in one place

  Renaming the sheet means editing one line.

• Column numbers

  Const COL_AMOUNT As Long = 5 → A column number with a name

  Cells(i, COL_AMOUNT) reads better than Cells(i, 5).

• Upper case names are the convention.
• Public Const at module level shares across modules.
• Built-in constants like xlUp and vbYes are Consts too.

• A Const cannot be assigned at runtime; use a variable if it must change.
• Const expressions must be literal, not function calls.