Meta tags are sections of code situated between the <head></head> tags of a web page.
When search engine optimisation first became popular Meta Keywords and Meta Description tags were very important in ranking your page. Today things have become more complicated but that doesn't mean these old school techniques are any less relevant.
The keywords meta tag was traditionally used by the first generation of search engines to analyse the content of the webpage.
Due to many websites misusing or not implementing it correctly it carries very little weight with search engines today, however it is still good website practice to use it correctly.
Think about what you expect people to type into 'Google' to reach your page (not your website), for example if you are selling Strawberry Jam then your keywords section could look like this...
<meta name="keywords" content="Jam,Strawberry Jam,Homemade Strawberry Jam,<your company> Strawberry Jam, Fresh Strawberry Jam, English Jam"
/>
Keep your keywords specific to the content of your page, so for example if you also sell Raspberry Jam then adjust your keywords for that page accordingly.
The description meta tag is commonly used by search engines as the description shown on their listings, its importance is often underestimated as whilst it does not carry as much weight as other tags it should been seen as the first impression somebody gets when reading about your site in the search engine results.
The description should be no more than 25-30 words, try to summarise the contents of the page in one sentence and in doing so make sure the most relevant keywords are included near the beginning of your text.
<meta name="description" content="Quality homemade
strawberry jam from <your company> - made in England using
traditional methods."
/>