Initializing Arrays - array = []*4
Multiple 1D arrays, finding equivalent ones [password and username] -

| Validation | Eg |
|---|---|
| Checks if something has been inputted | filling forms |
| Checks if it falls within range | age between 0 and 100 |
| Checks if it is reasonable length | password must have more than 6 chars |
| Checks if it is of proper type | age is numeric, rejects string |
| Checks that data item matches predetermined pattern | date of birth pattern |
| Check digit - Checks if numerical data has been entered accurately, extra digits are added to number based on calculation that can be repeated, enabling the number to be checked | barcode |
Verification -
Confirms the integrity of data, seeing if data is correct before and during and after processing
Spotting Errors -