So what does "Option Explicit" mean? Well, if you plan on using variables within your VBA code and inevitably you will, option explicit requires you to declare each variable.
How do I declare a variable? The syntax for declaring a variable within VBA is:
Dim [your variable name] as [Type of variable]
Dim MyVar as Integer
So what do I get out of using Option Explicit you ask? When the code compiles prior to running, you will receive an error message if you have a variable that has not been declared. This protects you from accidental typos of variables.
Using the example above, if I typed MVyar instead of MyVar and was not using Option Explicit - as long as the typo is not one of the VBA reserved words, methods or properties - VBA would by default assign MVyar as a new variable. This can make troubleshooting your code very difficult.
In conclusion, best practice states we should just set Option Explicit as a default setting. Here's How (Using Excel 2013):
- Open an Excel Workbook > Open VBA (alt + F11)
- Tools > Options > "Editor" Tab
- Check "Require Variable Declaration" (See picture below)