- Matching Email Addresses:

  - Example Text: "Please contact me at john.doe@example.com or jane@example.org"
  - Regex: `(?:[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,})`
  - Result: Matches `john.doe@example.com` and `jane@example.org`

- Extracting URLs from Text:

  - Example Text: "Visit our website at https://www.example.com or http://example.org"
  - Regex: `(?:http|https)://[^\s]+`
  - Result: Matches `https://www.example.com` and `http://example.org`

- Parsing CSV Data:

  - Example Text: "John,Doe,30\nJane,Smith,25\n"
  - Regex: `(\w+),(\w+),(\d+)`
  - Result: Matches `John,Doe,30` and `Jane,Smith,25`. Captures "John", "Doe", and "30" in group 1, 2, and 3 respectively for the first match, and "Jane", "Smith", and "25" for the second match.

- Extracting Hash Tags from Social Media Posts:

  - Example Text: "Check out our new product #launch #excited"
  - Regex: `#\w+`
  - Result: Matches `#launch` and `#excited`

- Extracting HTML Tags from Text:

  - Example Text: "<p>This is a <b>bold</b> statement.</p>"
  - Regex: `<[^>]+>`
  - Result: Matches `<p>`, `<b>`, `</b>`, and `</p>`

- Validating IPv4 Addresses:

  - Example Text: "The server IP is 192.168.1.1"
  - Regex: `\b(?:\d{1,3}\.){3}\d{1,3}\b`
  - Result: Matches `192.168.1.1`

- Matching Markdown Links:

  - Example Text: "Check out our website"
  - Regex: `\[(.*?)\]\((.*?)\)`
  - Result: Matches `[our website](https://www.example.com)`. Captures "our website" and "https://www.example.com" in group 1 and 2 respectively.

- Identifying Twitter Usernames:

  - Example Text: "Follow me on Twitter @john_doe and @jane_smith"
  - Regex: `@([A-Za-z0-9_]+)`
  - Result: Matches `@john_doe` and `@jane_smith`. Captures "john_doe" and "jane_smith" in group 1.

- Matching Scientific Notation:

  - Example Text: "The speed of light is 3.00e8 m/s"
  - Regex: `\b\d+(\.\d+)?[eE][+-]?\d+\b`
  - Result: Matches `3.00e8`

- Extracting YouTube Video IDs from URLs:

  - Example Text: "https://www.youtube.com/watch?v=dQw4w9WgXcQ"
  - Regex: `(?:youtu\.be/|youtube\.com(?:/embed/|/v/|/watch\?v=|/watch\?.+&v=))([^"&?/]+)`
  - Result: Matches `dQw4w9WgXcQ`

- Extracting Dates from Text:

  - Example Text: "The event is scheduled for 02/14/2024"
  - Regex: `\b\d{2}/\d{2}/\d{4}\b`
  - Result: Matches `02/14/2024`

- Identifying GitHub Repository Names:

  - Example Text: "Check out my GitHub repository: https://github.com/user/repo"
  - Regex: `github\.com\/(\S+)\/(\S+)`
  - Result: Matches `user` and `repo`

- Parsing Markdown Headings:

  - Example Text: "# Introduction\n## Subheading\n### Sub-subheading"
  - Regex: `^#{1,6}\s(.+)$`
  - Result: Matches `Introduction`, `Subheading`, and `Sub-subheading`

- Extracting Currency Values:

  - Example Text: "The price is $10.99"
  - Regex: `\$\d+(\.\d{2})?`
  - Result: Matches `$10.99`

- Identifying Twitter Hashtags and Mentions:

  - Example Text: "Great article! #DataScience is fascinating. @DataScientist"
  - Regex: `[@#][^\s#@]+`
  - Result: Matches `#DataScience` and `@DataScientist`

- Matching HTML Attributes:

  - Example Text: `<a href="https://www.example.com">Click here</a>`
  - Regex: `([a-zA-Z-]+)="([^"]+)"`
  - Result: Matches `href="https://www.example.com"`. Captures `href` and `https://www.example.com` in group 1 and 2 respectively.

- Extracting File Extensions:

  - Example Text: "The file is named document.pdf"
  - Regex: `\.([a-zA-Z0-9]+)$`
  - Result: Matches `.pdf`

- Matching JavaScript Function Calls:

  - Example Text: "Call myFunction(arg1, arg2)"
  - Regex: `\w+\(([^)]*)\)`
  - Result: Matches `myFunction(arg1, arg2)`. Captures `arg1, arg2` in group 1.

- Identifying Roman Numerals:

  - Example Text: "This is chapter IX of the book"
  - Regex: `\b[IVXLCDM]+\b`
  - Result: Matches `IX`

- Extracting HTML Comments:

  - Example Text: `<!-- This is a comment -->`
  - Regex: `<!--(.*?)-->`
  - Result: Matches `<!-- This is a comment -->`. Captures `This is a comment` in group 1.