When I talk about data type, I’m referring to the manner in which a program stores data in memory — for example, as integers, real numbers, or strings.
Although VBA can take care of these details automatically, it does so at a cost. (There’s no free lunch.) Letting VBA handle your data typing results in slower execution and inefficient memory use.
For small applications, this usually doesn’t present much of a problem. But for large or complex applications, which may be slow or need to conserve every last byte of memory, you need to be on familiar terms with data types.
VBA automatically handles all the data details, which makes life easier for programmers. Not all programming languages provide this luxury.
For example, some languages are strictly typed, which means the programmer must explicitly define the data type for every variable used.