SHA-1 is a mathematical algorithm to hash a certain string, which creates a one-way change from the source string to the result. It is commonly used for security and data loss, but there may be other cases. Computer programs exist to crack SHA-1 hashes by hashing random strings and storing the result. An example SHA-1 hash is "664add438097fbd4307f814de8e62a10f8905588" (the string "Wikipedia" hashed using SHA-1).