This process converts data into a cipher that cannot be easily understood:

The process that converts data into a cipher that cannot be easily understood is encryption. Encryption transforms plaintext into a scrambled format, or cipher, which protects the information from unauthorized access. This process uses algorithms and keys to ensure that only individuals with the appropriate decryption keys can translate the encrypted data back into its original, readable form. Encryption is a crucial aspect of data security, especially when sensitive information is transmitted over networks or stored.

In contrast, decryption is the process of converting encrypted data back to its original format, which is not relevant in the context of this question. Compilation generally refers to transforming source code into executable code, and segmentation is more about dividing data or memory into manageable parts rather than securing it. Thus, the focus on converting plaintext into an unreadable format confirms that encryption is the correct answer.