PCRE

PCRE stands for 'Perl Compatible Regular Expressions'. It is a way of searching for patterns in text. Let's say you wanted to find all the words in a document that start with the letter 'a'. You could use PCRE to search for the pattern "\b[aA]\w+" which means "a word boundary, followed by either 'a' or 'A', followed by one or more word characters".

In basic terms, PCRE makes it easier to search for specific things in a lot of text. Imagine finding a needle in a haystack, but instead of just blindly digging through the whole thing, you have a map that shows you exactly where the needle is. PCRE is that map, but for text.