Metadata is a set of tags used to describe a web page. It provides information such as page author, creation date, what the page is about and which keywords represent the page's content. A web browser does not display metadata but the machines accessing the page can access and efficiently record data from it. Many search engines use metadata for the creation of their indexes.
Make sure each of the pages of your site contain the following
Title tag
This is the text that appears on web page title bars and search engine results pages. This should be about 60-80 characters.
Description
This is the short line of text that is displayed in the search results of most search engines. This shouldn't be more than 100-200 characters.
Keywords
Keywords and phrases need to be relevant to the content and separated by commas. Avoid repeating a keyword more than 3 times.
Alt tags
Including keywords in alt tags can help your search results.
Keywords - some words are better then others
Keywords are words that users enter into search engines to describe the information/service they are looking for. You should make sure that you find keywords for your site that are relevant to your organisation and the field you are working in – look through the online and offline content produced by your organisation to find inspiration for this.
You should be careful not to choose a lot of terms that are very generic as they may be a lot of websites out there using these terms and this may not help to make your content easily finable. Also you should ensure that you include words that are being used by your target audience in search engines – you can use website statistics to find this information.
There are some free tools out there to help you choose keywords;