Who are the 144,000?

Webpages regarding the 144,000:

https://jesuschrististheking.com/144000-2/

https://davidjeremiah.blog/the-144000-in-the-book-of-revelation/

Are they kings, priests, and/or judges?

https://revelationscriptures.com/the-144000-what-the-bible-says/#144000_-_PRIESTS_KINGS_JUDG