Strings are sequences of bytes and appear in a few forms in the protocol.
Fixed-length strings have a known, hardcoded length.
An example is the
sql-state of the
which is always 5 bytes long.
Strings that are terminated by a  byte.
The length of the string is determined by another field or is calculated at runtime
A length encoded string is a string that is prefixed with length encoded integer describing the length of the string.
It is a special case of
If a string is the last component of a packet, its length can be calculated from the overall packet length minus the current position.