Blogger or Blogspot is a free blogging platform from Google. In blogger, you can create a blog for free and just in a few moments, you just need a google account (such as a Gmail Account) to start a blog instantly. If you are familiar with web applications like an gmail, facebook etc., that is enough to start a blog with blogger.
Anyway, though you can create a blog with just a few clicks, you might need some SEO tweaks to have your blog doing well in search engines. SEO (Search Engine Optimization) is a vast thing to discuss. In this post, we will only discuss about META keywords and descriptions in a blogger template.
META description is a small text description of what an webpage is all about. META keywords and descriptions are important parts of any website, such as your blogger blog. This two fields in your template helps the search engine bots to better understand the content of the page. Thus if you write a constant META description that appears in all of your blog pages, contents etc. then the search engine bot will not recognize each of your post well enough. For example, you might be having a post on cricket and another on football. Obviously a common description for these two posts will not help much a bot to understand the posts clearly.
There is an option at Settings > Search Preferences > Meta Tags where you can Enable Search Description by choosing YES and then can write a 150 Characters long text description. This text will appear as META Description for the homepage of your blog.
To write the META Description for each of your post and pages, just edit the post or page and find the Search Description text field in the right sidebar of the editor panel. Write the META description for the post or page in this text field.
Step 2 (If step 1 is not working):The first step is enough to work, but sometimes it may not work if you are using a custom template which may cause malfunction with this default option from blogger. In this case, you have to get your hands a bit dirty. Considering that you have Enabled Search Description as in Step 1, now do the following.
Go to Template > Edit HTML, to see the XML code for your blog. First of all find that if an <META /> tag for description already exist or not. If it exist then edit it as follows or add the following code inside your head tags.
<meta expr:content='data:blog.metaDescription' name='description'/>
And That's it. You are done. From now on, whenever you are writing a post or editing a static page, fill the text box at the right sidebar of the blogger content editor labeled as Search Description with the meta description for that post or page.
So in this way, the meta description you wrote at Settings > Search Preferences > Meta Tags will appear in Homepage and for other pages, descriptions you write at the that post or page will be used as meta description.