Spreadsheets were the first data tool most organisations used, and many still run on them.
Their strength is that the data and the calculation sit in the same place, in plain view.
Anyone can click a cell and see exactly how its number was produced.
A formula refers to other cells by address, such as B2, or by a range, such as B2:B50.
When a cell changes, every formula that depends on it recalculates.
Copying a formula down a column shifts its references, so each row calculates from its own values.
A reference written as $B$1 stays fixed when copied, which lets every row divide by one shared total.
Sorting, filtering and conditional colouring make odd values easy to spot in seconds.
Charts can be drawn straight from a selected range, which makes a spreadsheet good for a first look.
The weaknesses appear as the work grows.
Large files make spreadsheets slow, and every spreadsheet program has a hard limit on the size of a sheet.
Manual steps such as deleting rows or pasting values leave no record, so nobody can check or repeat them.
Errors hide easily, because a formula range that stops one row short still produces a believable total.
A common pattern is to explore in a spreadsheet, then move the steps into code once they need repeating.
The usual mistake is treating one shared spreadsheet as a database, with several people editing the only copy.