Data wiping is the process of eliminating all of the data stored on a hard drive or other data storage device. Under normal circumstances, data that is deleted isn't actually gone for good. Instead, all the pointers and indexes that reference that file are simply removed. While this renders the file inaccessible by normal means, much of this data can still be recovered through advanced data recovery techniques.

But what happens if you want to erase the contents of a hard drive for good? What if you don't want the data to be recoverable at all? In that case, you'll need to wipe your data completely.

The Basics of Data Wiping
Most modern data wiping solutions function in a similar manner. Instead of deleting your data outright, which would result in data that could potentially be recovered, these solutions actually overwrite the entire contents of your drive or data storage device. By writing a series of binary 1s and 0s in a random fashion, these data wiping solutions effectively render your data unrecoverable.

Some programs take this process even further with multiple passes. For example, the first pass might involve overwriting your data with all 0s, while the next pass will follow that up by overwriting the 0s with all 1s. While a greater number of passes ultimately makes your original data that much harder to recover, a single pass is good enough in most scenarios.

Data Wiping Algorithms and Standards
While one pass with a modern data wiping solution is good enough for the average computer user, some organizations and institutions actually maintain stringent standards regarding data wiping - including the frequency of which data should be wiped, how many passes the software should perform, and other rules. Some of the most common algorithms and standards are listed below.

• DOD 5220.22-M: This method is used by the Department of Defense (DoD) and the U.S. National Industrial Security Program (NISP). It involves writing a series of 0s in the first pass, 1s in the second pass, and then a random character in the third and final pass.
• NCSC-TG-025: Published by the U.S. National Security Agency (NSA), this method actually uses the exact same method as DOD 5220.22-M. However, this algorithm gives the user the opportunity to customize the process by adding more overwrite processes when needed.
• HMG IS5: Published and maintained by the Communications Electronics Security Group (CESG), the baseline version of HMG IS5 writes 0s during the first pass and a random character in the second and final pass. The HMG IS5 Enhanced algorithm writes 0s in the first pass, 1s in the second pass, and a random character in the third.

Although this isn't meant as an exhaustive list of the current data wiping algorithms and standards, it does cover the most common ones in use today.

Wiping Your Data
Remember, it isn't enough to simply delete your data. To truly render your data unrecoverable, it's essential that you perform at least one pass from a full-scale data wiping solution that follows one of the common data wiping algorithms.

You may read more about data wiping in Wikipedia: Data erasure.