Charat operator outside the square brackets in regex java

Question

I have three patterns

Pattern pattern = Pattern.compile("[a-f]"); // Pattern 1
//Pattern pattern = Pattern.compile("[^a-f]");// Pattern 2
//Pattern pattern = Pattern.compile("^[a-f]");// Pattern 3

Matcher matcher = pattern.matcher("acdefghijklmn");
while(matcher.find()) {
    System.out.print(matcher.start() + " ");
}

Results :
Pattern 1 - 0 1 2 3 4
Pattern 2 - 5 6 7 8 9 10 11 12
Pattern 3 - 0

I know Pattern 1 is for finding any simple letter between a and f(inclusive) and Pattern 2 is for finding any simple letter not between a and f (inclusive). But what does pattern 3 mean?

Answer 1

But what does pattern 3 mean?

Pattern 3 ^[a-f] macthes when a string starts ^ with [a-f].

Answer 2

"^[a-f]"

Means letter a-f is matched at the line start.

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Answer 3

But what does pattern 3 mean?

^ outside the [] means at the start of the String just like $ means at the end.