Your pictures on your website are a great place to lace the website with keywords without compromising the organic feel of the content. By tagging photos with keyword heavy names and phrases, page ranking may be improved.
Web traffic can also be improved through image search results. A user clicking on an image that is relevant to your website may be intrigued by the page that it is pulled from and click-through to it. Search engines such as Google have also started incorporating images into regular search results, and it is for this reason that images need to be tagged properly with SEO principles in mind.
It is not only primary pictures on the website that need to be tagged, secondary pictures can carry just as much weight. Therefore smaller photos, logos, and icons needs to be tagged too. The more information that a crawler has to work with, the more your page ranking will improve.
When tagging photos be sure to be specific and keep the tags related to your website content. This does not mean that photo tags should not be relevant to the photos either. Keep photos relevant to the content of your website too. SEO is about creating a website that is about a topic and produces original and unique content about the topics, including pictures.