.*any character (except for line terminators), repeated any number of times
\ban ASCII word boundary
hellothe literal text hello (case sensitive) \s+any whitespace character, repeated at least once
.*?any character (except for line terminators), repeated any number of times
\s+any whitespace character, repeated at least once
worldthe literal text world (case sensitive) \ban ASCII word boundary
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string