I am sure you know the importance of formulae in Mathematics or Physics, thanks to which our tasks have become simpler. We just provide the input and expect an output without diving deep into the logical statements. However, being in the IT world, logic is a part of day-to-day activities. If you have used MS Excel, you will know how helpful formulae are, especially VLOOKUP, Transpose, and so on.

For the workflow criteria, approval process criteria, formula fields, validations, and many more scenarios, you will come across an advanced formula editor, which will provide you with the ability to write some logic using the merge fields concept, and some common logical and mathematical operators, text, date, and so on.

For a comprehensive list, I would recommend that you refer to the document at https://help.salesforce.com/HTViewHelpDoc?id=customize_functions.htm&language=en_US.

The formula editor will look as shown in the following screenshot. It is available when you create a formula...