What does data encryption achieve?

Data encryption is a security measure that transforms readable data into an unreadable format, known as ciphertext, using algorithms and encryption keys. This process is essential for protecting sensitive information from unauthorized access. When data is encrypted, even if it is intercepted during transmission or access is attempted without permission, the information remains secure and cannot be interpreted without the proper decryption methods. This capability is crucial for safeguarding personal data, financial information, and confidential communications, as it ensures that only authorized users can read the original content.

The other options do not accurately represent the purpose of data encryption. For instance, speeding up data transfer is not a function of encryption; in fact, encryption can add overhead to data operations. Compressing data relates to reducing file size rather than altering its readability. Ensuring data is correct and unaltered refers more to data integrity and validation processes rather than encryption itself, which focuses on data confidentiality.