Final answer:
The SHA-224, SHA-256, SHA-384, and SHA-512 algorithms are collectively known as SHA-2 (Secure Hash Algorithm 2), which denotes a family of cryptographic hash functions.
Step-by-step explanation:
The SHA-224, SHA-256, SHA-384, and SHA-512 hash functions are known collectively as SHA-2 algorithms. They are variants of the Secure Hash Algorithm 2 (SHA-2) family, which serves as an essential set of cryptographic hash functions widely used in various security applications and protocols, including TLS and SSL, PGP, SSH, and IPsec.
The numbers in each variant's name, like 256 or 512, indicate the bit length of the hash output, providing an insight into the strength and usage case of each algorithm.