A more thorough explanation:

Definition: A hash number is a unique numerical code that is generated by encryption software. It is used to create a digital signature, which is a way to verify the authenticity of a message or document.

For example, when you sign a document electronically, your computer generates a hash number based on the contents of the document. This hash number is then encrypted using your private key, creating a digital signature that can be verified using your public key.

Another example is when you log in to a website using a password. The website doesn't store your actual password, but rather a hash number that is generated based on your password. When you enter your password, the website generates a new hash number and compares it to the one stored in its database. If they match, you are granted access.

The use of hash numbers is important for security because they are virtually impossible to reverse-engineer. Even if someone were to intercept your digital signature or the hash number used to verify your password, they would not be able to use it to gain access to your account or forge your signature.