Due to a design flaw, SHA had weaknesses that led to a correction as early as 1995. The correction consists only of a small detail in the key division, but not in the number of rounds passed or other measures that would immediately lead to the expectation of significantly higher security.
The corrected algorithm was named SHA-1.
In the meantime, four other variants of the algorithm have been published that produce larger hash values. These are SHA-224, SHA-256, SHA-384 and SHA-512, where the appended number indicates the length of the hash value (in bits). Later, the versions SHA-512/256 and SHA-512/224 were added.
These further developments are often summarized under the designation SHA-2. They are based on the same design principle as SHA-1, except that the internal data block has been increased to 256 and 512 bits, respectively, and the block cipher on which the compression function is based has been modified.