Another article about the importance of alt tags on images in blogs...
http://peppercorncreative.com/alt-tags-image-titles-file-names/
Priority #1: Alt Tags
Out of everything, the single most important thing you need to worry about with your images is the Alt Tag (Alternative Tag). Alt Tags are what the browser will display if the actual photo can’t load or if for some reason the reader has images turned off on their browser. Think of it like the hidden title behind the actual picture. So, it only makes sense that as Google crawls down your page, it looks at the Alt Tag to determine what the picture is actually about so it can index the image correctly in search results. In addition,
the Alt Tag is the first place Pinterest looks for the pin description. It then looks for the Image Title Tag (#3 below) and lastly, the page title if it can’t find anything else.
If you’re using WordPress, you can edit the Alt Tag when you upload a file.
If you’re using Blogger, you can edit the Image Properties using this guide. If you’re on another blogging platform, you should have similar functionality somewhere in there! It doesn’t matter where it happens, as long as it gets done.