BASICS
Matching literal text
The simplest pattern is the literal text you want to find.
The pattern cat finds the three characters c, a, t in a row. Most characters mean exactly themselves - you type the text you are hunting for and the engine finds every place it appears. A few characters are special instead: they are called metacharacters (like ., *, ?) and stand for a rule rather than themselves. To match one of those literally, you escape it, covered later.
A pattern matches anywhere inside the text, so cat also matches the middle of "concatenate". Limiting matches to whole words comes later. (These drills always match globally - every occurrence is highlighted.)
Match every occurrence of the word cat, including when it sits inside a longer word.
my cat sleeps all day
concatenate the strings
cat catalog cathedral
a dog barks
Match every occurrence of art, including when it is buried inside a longer word.
the art of war
depart from the start
a smart cart
no match line