ALT tags (alternate text), the HTML tag that provides alternative text when non-textual elements, typically images, cannot be displayed.

1. Image Alt text non-hyper linked When an ALT tag is used mainly to describe an image with some alternative text, this can help your page relevancy. In other words if ALT attribute contains keywords that are specific to your page's topic will help your keyword density. Otherwise, unique text into ALT attribute text doesn't appear anywhere else in the page that will not influence Googlebot when spidering and indexing your page.

2. Image ALT text hyper linked The ALT tag of a hyper linked image which means the "a href" tag seems to have the same importance of a text link. Therefore Google index it as a simple text link.

3. Image size Google has the ability to check images' size, and a link on a too small image is automatically considered an illegal technique. Even if do not specify width and height in IMG tag.

4. Image link on the page Giving images on the web page, images create the link on the page. When we define image on the page image shows the complete path of itself in the URL form. For example, http://www.example.com/images/seo.jpg seo.jpg is the image of examle.com, home page. This image creates the path to call the images from the FTP server. And on live page, it shows in the URL format. It may say the outbound link of the page. Also, this image source link does not give any back link to the home page. From the page as many number of image source links, that many number of outbound links, according to my assumption. Since, image is not in the hypertext link form, it doesn't impact as a big issue. Because, the outbound links mainly concern to the links which carry forward on another page.

However, images without hyperlink are physically placed on any page. No action from any image since they are not by hyper linked.

5. How Google image search works Google analyzes the text on the page adjacent to the image, the image caption and dozens of other factors to determine the image content. Google also uses sophisticated algorithms to remove duplicates and ensure that the highest quality images are presented first in results. Google Image Crawler: Agent_String: Googlebot-Image/1.0 (+http://www.googlebot.com/bot.html)

6. Important point for image optimization: 1. Image "alt" Text 2. Image "title" Text 3. Image File Name 4. Image Folder Name 5. Page Title 6. Page Content 7. Page URL

7. Optimize ALT Descriptions For Search Engines:

Besides helping visitors, ALT descriptions help rank higher in some search engines. AltaVista and Google are two of the search engines that use ALT descriptive text when they rank Web sites. The growth of search engine/directory partnerships means that a high rank in one engine can often translate into an improved rank on its partner sites.

Search engine algorithms calculate the number of times keywords are repeated and give higher rank to pages that use them often. Keywords in the ALT descriptive text help to increase their frequency on the page. Search engines assume the terms are more relevant and important if they are used in the page content, not just listed in the META tag.

Google does index image links, but without any text, it does not help link popularity rating for important keywords.