Favicon is the small image appearing on browser tab besides the title of the blog or webpage. That favicon is actually an image with .ICO extension. There are lot many other ways to create a ICO file on your computer, For example IrfanView is a free image editing software which creates ICO files, but if you are having Adobe Photoshop then no need to have any other software to create favicon. The problem is that Adobe Photoshop does not support ICO extension by default i.e. you can not save an image as ICO thru Photoshop.
To do that you need to have Adobe Photoshop ICO Plugin which enables the user to save image as ICO file. For favicons, you need very small size image like 16px x 16px and in that image you will have to show your creativity which can be done thru Photoshop. Here is the plugin you need to download for this purpose:
Now install this plugin on your computer and start creating the favicon file on a canvas size of your choice. You may prefer 64 x 64 pixel canvas as you can put colors on that easily. After completing the design, resize the image to 16 x 16 pixel and then save image file as ICO file by selecting “File type” from the Save As window.
Upload the favicon to your blog/website directory and link that favicon in header section of your webpage/blog. Now you can create different icons like Windows Icons etc using Adobe Photoshop.