A block in Perl is a series of statements grouped together by curly brackets. Blocks can be used in conditional constructs and subroutines.
A conditional construct is one which executes statements based on the truth of a condition
Truth in Perl is determined by testing whether something is NOT any of: numeric zero, the null string, or undefined
The if - elsif - else conditional construct can be used to perform certain actions based on the truth of a condition
The while, for, and foreach constructs can be used to repeat certain statements based on the truth of a condition.
A common practical use of the while loop is to read each line of a file.
Blocks may be named using the NAME: convention
You can break out of blocks using next, last and similar statements