What is a Meta Tag
A meta tag is an HTML line that contains metadata about a webpage. Meta tag information won’t be seen by the website viewer, unless they are viewing your source code. In other words it don't affect how a page looks like at all. The main purpose of meta tags is to inform the search engine bots about your page.
These meta tags are placed within the <HEAD> </HEAD> tags of the HTML code.
There are two common meta tags
As the name implies, the meta description tag describes what the page is about in one or two short sentences.
This is how the description tag of this page should look like:
<META name =“description” content="This page contains all the information on Meta Tags">
The meta keywords tag lists some words in it which are used time and again in the page and show what page is really about.
This is how the keywords tag of this page should look like:
<META name ="keywords" content="meta tags, meta, seo, keywords, description, optimize ">
Can Meta Tags rank you higher in SERPs?
The short answer is 'yes' for certain search engines and a 'no' for others. Google currently don't seem to give much value to them but in future they might have a look at them. Optimizing them can save you from falling in SERPs. In addition to keep you from ranking low, they also improve your search engine rankings(of some search engines) and rank you high for the rite queries which send targeted traffic to your site. I understand they have lost their importance because of spamming which not all but only a few webmasters did, but still many search engines give value to them.
What if I don't have Meta Tags on my pages?
That is no more a problem. They are no more as important as they were 3-4 years ago. But if you have them, you should optimize them or remove them. Its either optimized meta tags or no meta tags at all. But as I say before there is no harm in following the guidelines given by search engines and according to their guide lines you should have meta tags. There is a saying in SEO: "You should use everything available to you that the engines might give some weight, and therefore you should certainly use meta tags." So do use them wisely.
How to optimize Meta Tags
The only way to optimize them is to write them wisely. Write a genuine description in the description tag. The description should be short and related to the page. Choose keywords wisely. Don't over stuff the keyword tag. Don't put words like 'there' and 'end' in the keyword tag, just the keywords that are related to your topic. Remember never repeat keywords in the keywords tag or it will be seen as spam.