<iframe matches the characters <iframe literally (case sensitive)
Match a single character not present in the list below [^>]*?
*? Quantifier — Matches between zero and unlimited times, as few times as possible, expanding as needed (lazy)
> matches the character > literally (case sensitive)
title= matches the characters title= literally (case sensitive)
1st Capturing Group (\\\'|\\"|[\'"])
\\ matches the character \ literally (case sensitive)
\' matches the character ' literally (case sensitive)
\\ matches the character \ literally (case sensitive)
" matches the character " literally (case sensitive)
Match a single character present in the list below [\'"]
\' matches the character ' literally (case sensitive)
" matches the character " literally (case sensitive)
2nd Capturing Group ([^>]*?)
Match a single character not present in the list below [^>]*?
*? Quantifier — Matches between zero and unlimited times, as few times as possible, expanding as needed (lazy)
> matches the character > literally (case sensitive)
\1 matches the same text as most recently matched by the 1st capturing group
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)