The parenthesis operator ( is also useful when we are using counters like the Kleene*. Unlike the | operator, the Kleene* operator applies by default only to a single character, not to a whole sequence. Suppose we want to match repeated instances of a string. Perhaps we have a line that has column labels of the form Column 1 Column 2 Column 3. The expression /Column [0-9]+ */ will not match any number of columns; instead, it will match a single column followed by any number of spaces! The star here applies only to the space that precedes it, not to the whole sequence. With the parentheses, we could write the expression /(Column [0-9]+ *)*/ to match the word Column, followed by a number and optional spaces, the whole pattern repeated zero or more times.