What is meta tag Optimization ?
Meta tag nowadays dont play a major role in SEO, but they should be included in your web page as they might help in you getting good SERP in other search engines excluding google.

Description meta tag 

This tag is very important & still googlebot uses this description tag to show description of your website whenever a relevant search query is fired by the user.

<meta name="description" content="Description of your website"/>

Please note: In description you have to give the description of your own website i.e describe what your company does or provides in suitable manner please dont try to proove how your company is great than others it might effect your SERP.
Robots meta tag
This tag is used to inform search engines which pages to index & which not to index
content="all " means all the pages are indexed & followed by the search engines.
content="Index,follow" means it tells the search engine index the current page & follow the other pages as well.
similarly there are index,nofollow
noindex,nofollow

<meta name="robots" content="All"/>