Some Blogger may forget to use "alt" in the picture, though fairly simple, but the effect was great to get traffic from search engines like Google, Yahoo, Bing, etc.
You need to remember search engines (Google, Yahoo, Bing, etc.) can not read images, Search engines can only read the image title and the "alt tag" the image, so that we could insert certain keywords and certainly very helpful for our image found on search engines.
Especially for those who access a website / blog via mobile phone (Mobile Web) and also having a slow connection when you access a blog page. As they search for images are list-list writing and alt tags are very useful here.
"Alt tag" for the image is very important. Try your search on google images, in the bottom of each image there is a source image, ie sites that display the image. When you match, you will click twice to see the actual size. Well, the first stage after clicking the window will pop up a blog with the picture viewer. So that's fortunately if from a search engine user clicking our pictures and they ended up stuck on our blog, surely it would be additional traffic to our blog.