The re module in Python provides full support for regular expressions — powerful tools used to search, match, and manipulate strings based on specific patterns.

Import the Module

import re

1. re.search() – Find First Match

import re
text = "The rain in Spain"
match = re.search("rain", text)
print(match)

Output:

<re.Match object; span=(4, 8), match='rain'>

Explanation:
re.search() searches for the first occurrence of the pattern and returns a Match object.

2. re.findall() – Find All Matches

import re
result = re.findall("ai", "The rain in Spain")
print(result)

Output:

['ai', 'ai']

Explanation:
re.findall() returns all occurrences of the pattern as a list.

3. re.match() – Match at Start of String

import re
result = re.match("The", "The rain in Spain")
print(result)

Output:

<re.Match object; span=(0, 3), match='The'>

Explanation:
re.match() checks for a match only at the beginning of the string.

4. re.sub() – Replace Using Pattern

import re
result = re.sub("Spain", "India", "The rain in Spain")
print(result)

Output:

The rain in India

Explanation:
re.sub() replaces all occurrences of the pattern with a new string.

5. re.split() – Split by Pattern

import re
result = re.split("\s", "The rain in Spain")
print(result)

Output:

['The', 'rain', 'in', 'Spain']

Explanation:
re.split() splits the string using the given pattern (\s means any whitespace).

6. Meta Characters & Patterns

7. Grouping and Extracting

import re
text = "My phone number is 987-654-3210"
match = re.search(r"(\d{3})-(\d{3})-(\d{4})", text)
print(match.group())
print(match.group(1))  # Area code

Output:

987-654-3210
987

Explanation:
Use parentheses () to group parts of the match and group(n) to extract them.

8. Flags (e.g., re.IGNORECASE, re.MULTILINE)

import re
result = re.search("hello", "Hello World", re.IGNORECASE)
print(result)

Output:

<re.Match object; span=(0, 5), match='Hello'>

Explanation:
re.IGNORECASE makes the match case-insensitive.

9. Raw String r'' in Regex

Always use raw strings for regex patterns to avoid escaping backslashes:

import re
pattern = r"\d{3}"

Summary Table