BASICS
Escaping
When you mean a literal dot, say so: backslash it.
The pattern 3.14 does not mean "3.14" - the dot matches anything, so it also matches "3414" or "3x14". To match a literal metacharacter, escape it with a backslash: 3\.14.
Characters that need escaping: . * + ? ^ $ ( ) [ ] { } | \. When in doubt, escaping a punctuation character is always safe.
Match the exact text 3.14 - and nothing that merely looks like it.
/ /
pi is 3.14 roughly
must match: "3.14"
the code 3414 is not pi
must match nothing
3x14 is not pi either
must match nothing