How are variable pages indexed by Google?

Question

For example, I have a website that allows users to post articles. I also want them to appear on Google Search results. Usually, after you submit a sitemap, Google takes a few days or weeks and sometimes even months to crawl it. Then how do Stack Overflow questions, etc appear on search? The user could also delete/rename those posts. Surely... They don't have to wait a few days. So.. How are such varying urls crawled by Google?
Thanks in advance. 🙂

Answer 1

Bagon , Thanks for replying. But they submit the URLs to Google. www.sololearn.com/discuss/1562...
Each post has a different url.
I want to know how is it done without a sitemap.
If we submit URLs to Google. search.google.com/search-console/
It takes time to index..