WordPress post featured image is an image which is associated and appeared with the post as designed in user’s theme specifications. WordPress featured image was first introduced in WordPress 2.9 and the term used at that time was post thumbnail but the term was changed to Feature Image later on. It is also called WordPress post header image.
You can add featured image to WordPress post by simply creating a new post and clicking Set featured image on bottom right corner and either select or upload your image.
Use featured image with posts whenever possible because posts with featured image gets 43% more visibility.Woopoo's Tip