Question posted in 
what is the differences the lists below:
<meta name="robots" content="index, follow">
<meta name="robots" content="follow">
<meta name="robots" content="noindex, follow">
<meta name="robots" content="index, nofollow">
<meta name="robots" content="noindex, nofollow">
3
Answers
The main difference between these tags is, in very simple words:
noindex
The page is supposed to not be shown in the result list of pages like google, yahoo and so on.
index means the opposite and allows it.
nofollow
Disallows crawlers/robots to call (follow) links that are embedded in / found on pages that carry this flag in their meta data.
follow means the opposite and allows it.
Now you can figure out yourself what each combination of both results in. 😉
The spider will index your whole website.
The spider will not only index the first web-page of your website but also all your other web-pages as it crawls through links from this page.
Tells the search engines that it may follow links on the page, to discover other pages. (both of these are default behaviour)
The spider will now index your whole website. The spider will not index the web-page but it may follow links on the page, to discover other pages.
The spider will index this page but it won’t follow links on this page to new pages.
The spider won’t index this page at all and won’t follow links on this page to any other pages.
Sources:
https://www.metatags.org/meta_name_robots
https://yoast.com/robots-meta-tags/
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-name
First of all, do you know about Meta Robots Tags?
Meta Robots Tags is to tell the spider or crawler which page to crawl or index or not.
Follow means : page will be crawled.
No Follow means : page will not be crawled.
Index means : your page show in search Results.
No Index means : your page does not show in search Results.
This tag tells the web crawler all pages will be indexed and to crawl them.
This tag is used to tell the web crawler all pages will be crawled and indexed.
This tag is used to tell the crawler to follow but not index the page in your database.
To tell the web crawler page not crawl but index them.
To tells the web crawler to neither index nor crawl.