Excerpts can be created using the WordPress More quicktag. Quicktags are like HTML formatting tags, but they only work within WordPress. Should you use excerpts? Yes, and here is the reason why.
It is never a good idea to display an entire post on the home page or the category pages. Why? Because if you want your blog pages to rank well with search engines, it is important to have have one and only one page representing your content. Multiple copies of an article create duplicate content.
Duplicate content is commonly penalized by search engines, so if you are displaying an article on the home page, a category page and in the post itself, which one will a search engine spider select as the original article? That is not always predictable, and you want to give the article the best chances for high search engine rankings. That is why experienced WordPress bloggers only display the first few sentences of an article on the home page and category pages. A few sentences do not create duplicate content problems, but a copy of an entire article does.
The More quicktag is inserted at the point where the excerpt should end. As we mentioned, that is usually after the first few sentences in your blog post. Think of the excerpt as kind of a “teaser” intended to invite curious readers to view the blog post and word those sentences accordingly.
The use the More quicktag, simply position the cursor at the point where you wish to insert the quicktag. Then just click on the More button on the editor’s tool bar and the tag will be inserted.
Once the post has been published using the More quicktag, you should only see the excerpt for the article displayed in any article listings.