When you publish a post the post will also usually be shown on your blog home page. It is normal to show the last five to 10 posts on your blog page. The newest post always in the top position. If you have long posts (great for your search engine optimisation) this can make your home page very long to the point of it not being a benefit to your visitor. However in Wordpress you can use the Read More tag you can cut-off the post at a suitable place on your home page but add a link to the full post where a user can read the full post, add comments and like plus1 or whatever you invite them to do.
To insert a Read More tag: