Page Information

application-name

Giving the name of the Web application that the page represents.

<meta name="application-name" content="OpenStreetMap">

If it’s not a Web application, the application-name meta tag must not be used.

author

Set the author of the page:

<meta name="author" content="Your Name">

Only one name can be given.

description

Set the description of the page:

<meta name="description" content="Page Description">

The description meta tag can be used by various search engines while indexing your web page for searching purpose. Usually, the description contained within the meta tag is the short summary that shows up under the page/website’s main title in the search engine results. Google usually uses only the first 20-25 words of your description.

generator

<meta name="generator" content="HTML Generator 1.42">

Identifies one of the software packages used to generate the document. Only to be used for pages where the markup is automatically generated.

keywords

Set keywords for search engines (comma-separated):

<meta name="keywords" content="Keyword1, Keyword2">

The keywords meta tag is sometimes used by search engines to know the search query which is relevant to your web page.

As a rule of thumb, it is probably a good idea to not add too many words, as most search engines that use this meta tag for indexing will only index the first ~20 words. Make sure that you put the most important keywords first.