For Each ... Next visits every item in a collection: cells in a range, sheets in a workbook, files in a folder. No counter needed.

Code

For Each ws In ThisWorkbook.Worksheets
  ws.Visible = xlSheetVisible
Next ws

• Every sheet

  For Each ws In ThisWorkbook.Worksheets ws.Visible = xlSheetVisible Next ws → Unhides every sheet

  Sheets.

• Every cell

  For Each c In Range("A2:A100") If c.Value < 0 Then c.Font.Color = vbRed Next c → Reds every negative

  Cells.

• Dictionary keys

  For Each key In dict.Keys Debug.Print key, dict(key) Next key → Every entry in a Dictionary

  Dictionaries.

• Declare the loop variable as the item type (Worksheet, Range) for autocomplete.
• For Each over cells is slower than an array for large ranges.
• Do not add or remove items from the collection while looping it.

• Deleting sheets or rows inside a For Each skips items.
• The loop variable for a range must be Range or Variant.