A Long-Time Tradition and Attraction
Brick and mortar businesses have done it for ages. Google does it with "Google Doodles" for many occasions. Almost all the large websites do it. If you do it well, visitors may come to your site regularly just to see what you're doing with it currently. Decorate your website graphically for the season, holiday or event. Or memorialize an important date. Or announce a happy occurrence.
I remember as a child that my parents would take us to see what department stores had done with their display windows for major holidays. The stores would vy with one another for the best themes and animations. Christmas was always the most elaborate, with the most whimsical moving displays. One year, the most popular window display was the typical Santa, elves and reindeer moving around a roller-coaster track.
You don't have to be elaborate. In fact, you need to be aware of how the graphics you add will affect your page load time. Just some small artwork remindful of the season or event will do. I used to simply provide a printable poster for Halloween, for example. I haven't done that in a while. Maybe I'll reinstitute the practice this year.
You don't even have to do your own artwork. Just get relevant clip art available for no cost at many, many websites. You also don't have to wait for major events. You can run a new graphic every day based on a "today in history" theme.
Here's why it influences traffic for your site:
Creates A "Human" Atmosphere
Appearance is part of the usability of a site. The more visually attractive the site, the more likely the visitor is to look around. As the visitor looks around, he discovers more of the features of the site and how to navigate the site.
A big part of appearance is comfort and familiarity. The more "humanized" your site, the more comfortable and familiar it becomes. By "humanized" I mean that it looks like it was created by a real person, who gave thought and consideration to what would serve other people using the site. It's not just a bunch of sales pages, data displays, order buttons, testimonials and exhortations to buy, buy, buy.
When you decorate, folks get the impression that there's a real individual behind the site. One that is trying to communicate with them. One who actually cares whether or not the site is attractive and enjoyable to visit. They are more likely to stay to see your offers or visit again later to see what's going on.
Shows That Your Site is Up To Date
People want to be able to count on consistently finding the content they've found before on your site. They also want new and more content. If they see changed graphics when they visit, they get an immediate impression that you are updating the site and providing new content.
So, your site is "stickier" and more bookmark-able.
Draws Attention To Special Offers
Nothing on a website attracts attention like graphics and enhanced typefaces. The eye goes immediately to images. So if you have something new going on, make an event graphic for it. If you can tie it in to an actual event or holiday, all the better.
Come on. Just as most folks like to dress up themselves or their homes for a party or holiday celebration, website designers love to dress up their sites for events. Even if you are a solo entrepreneur working on your own site, using support software that requires no coding, you can do this. It's like child's play. That is to say, you get in the spirit and play like a child. You enjoy it. Your customers/clients/visitors enjoy it.