The Free On-line Dictionary of Computing (30 December 2018):
The loop construct, found in nearly all
procedural languages, that executes one or more instructions
(the "loop body") repeatedly so long as some condition
evaluates to true. In contrast to a repeat loop, the loop
body will not be executed at all if the condition is false on
entry to the while.
For example, in C, a while loop is written
while () ;
where is any expression and is any
statement, including a compound statement within braces
A for loop, e.g. in the C language, extends the while loop
syntax to collect pre-loop initialisation and loop-end logic
into the beginning of the statement.
Perl provides the "until" loop that loops until the loop
condition is true.