ALT is an attribute of the IMG Tag. <img src="your image.jpg" alt="My Text" Title="My Title" width="40" height="17">
They are both properties you add to an image. From the human user's perspective, the ALT property is only used if they have configured their browser not to show images, or if they are browsing from some kind of "text-only" browser. The Title property may or may not be seen. Some wordpress themes add the title below the image, as if it were the image caption. Some browsers also show the title as a tooltip when you hover over the image. From an SEO perspective, the ALT title seems to be the most important, as it's the one that web crawlers use to determine what an image is about. So, and image with an ALT title that says "dog training" would add a bit more on-site "weight" to your site for the "dog training" keyword.
“Alt†stands for “alternative text†and is an attribute (most people call it a “tagâ€) that is shown when an image cannot be displayed. I’m sure that even those of us who don’t use screen readers can think of times when this might happen. Emails are a perfect example. I have to click a button when I get an email that enable images. If there is no “alt†text on those images, and the email is 100% images, guess what I see before I click the “display images†link? Right. I see nothing. “Title†stands for “title text†and is an attribute that should only be used if your image is clickable, that is to say it clicks thru to another Web page. While the “alt†tag should always be included on an image tag, the “title†tag only needs to be included to give your visitors some idea of where they are going if they DO click on the image. Source
Alt text and title are the properties of image that you can add to image. According to my viewpoint, Alt text and title properties of image both are useful in Image Optimization. Alt text gives the alternative information to people who have selected to eliminate images in their browsers and those user agents that are simply unable to see the images. It should explain what the image is about and get those visitors fascinated to see it. On the other side, image title provides additional information to image. While search engine optimization, you need to make sure that it should be appropriate, short, appealing and to the point. In browsers it pops up when you mouse over an image.
Image title mean . Image Name and if you want to make SEO friendly this image . then put Alt Tag with image and keep your keyword there but some different word as your image title.
Google crawler couldn't see what the image is about you're using on your website. Alt tags helps crawlers in identifying the image in simple language.
Title and Alt both are the properties of <img src=" "> tag. In simple world Title for users reference and Alt for search engine crawlers reference.
Image title (and the element name speaks for itself) should provide additional information and follow the rules of the regular title Alt text is meant to be an alternative information source for those people who have chosen to disable images in their browsers and those user agents that are simply unable to “see†the images.