Favicon is small image appearing in the browser for a website. It is used for branding. Almost every popular website uses favicon to distinct their websites from others.
As a example have a look on the below screenshot, where favicon of two websites are shown.
If you are looking to add the same Favicon for your wordpress blog, then you need to first create a favicon. The standard size for most of the Favicon is 16×16.
You can create a simple favicon in Paint, Photoshop or any other drawing program. You can also use http://www.favicon.cc/ to generate a free Favicon for your blog.
In either case, make sure to save the image in .ico format.
Once you have the Favicon, upload it to your blog through Media>Add New
How to Display Favicon in Browser Tabs?
Open header.php file from Appearance>Editor
Copy the code mentioned below and past in your blog </head> section.
<link rel=”icon” href=”http://www.yourdomain.com/favicon.ico” type=”image/x-icon” />
<link rel=”shortcut icon” href=”www.yourdomain.com/favicon.ico” type=”image/x-icon” />
Make sure to enter the URL of your Favicon in the above code. Save the file and FavIcon will be added for your blog in all the browsers.