What could cause for a page to get not indexed?

[sophiawils59]

What could cause for a page to get not indexed?

[jayam]

Your Site is Indexed Under a www- or Non-www Domain. Technically www is a subdomain. ...
Google Hasn't Found Your Site Yet. ...
The Site or Page(s) are Blocked With robots. ...
You Don't Have a sitemap. ...
You Have Crawl Errors. ...
You Have Lots of Duplicate Content. ...
You've Turned On Your Privacy Settings. ...
The Site is Blocked by .

[rscomponentseo]

A website might not be well connected through multiple links from other sites on the web.
The design of the website might make crawling and indexing difficult.