are custom equations you create yourself to perform calculations, such as =A1+B1 .
Every formula and function must begin with an equal sign. This tells Excel that the cell contains a calculation rather than just plain text. Microsoft Excel Functions and Formulas
are predefined, "built-in" formulas already available in Excel, such as =SUM(A1:A10) . Core Principles are custom equations you create yourself to perform
Instead of typing numbers directly (e.g., =10+5 ), it is best practice to use cell references (e.g., =A1+B1 ). This ensures the result updates automatically if the values in those cells change. Essential Functions for Every User Overview of formulas in Excel - Microsoft Support "built-in" formulas already available in Excel