A Favicon is, generally, an image, which displays above the URL in the Browser Tab. It can personalise your site/blog. Favicons are limited in size to 16px x 16 px. You can either create them yourself, using Irfanview, or MS Paint, or use a website, like Favicon & App Icon Generator... I just download the finished Favicon - not the 'code'.
Different Browsers have different requirements, as far as image file formats are concerned; eg: .ico , .png , jpeg, gif , etc., and different sizes 16 x 16, 32 x 32, 48 x 48 pixels, etc. I use Google Chrome, or Firefox, and have NO problems with a square image less than 100 Kbs ... coloured, or not, but it's worth looking at the table in the Wikipedia link (above).
The way I add a Favicon is:
- 1. Create my icon on MS Paint. Make it square. Size it to 40 x 40 px.
- 2. Go to the Layout screen. Edit the Favicon Page Element. Choose a file which I prepared. Upload it.
- 3. I don't touch the blog template - at all. All adding is done through the Layout screen. No codes.
- 4. Save. Wait until Google does it's job, which sometimes takes a few days!
The Finished product ...