Are animation*, sound or video a good idea?

Usually the answer is no.

Think about it. Look at where animation is most used - in adverts. Adverts on a web page are designed to attract you away from the page you are looking at. They are all clamouring for your attention until you give in and click one of the little blighters.

If your home page has scrolling text, whirling logos or even subtle animation, these animated elements will serve only to distract people away from the words you have carefully crafted for your web page.

Remember that you are not trying to attract someone's attention from across the street. They are already looking at your website, and are in a receptive frame of mind, they want  to read what's on the page and you're making it more difficult for them by moving things about.

That's just our opinion from a usability point of view, but it depends on the website and your market. Sometimes a bit of Flash just says 'hey look, we can afford some fancy trimmings', which is fine if that is what your market is influenced by.

Sound that plays as soon as a web page loads is almost universally seen as a bad idea. The kids are in bed and your potential customer goes to your website looking for car accessories. He's playing some music through the PC and suddenly, a loud and unwelcome 'Vvvrooom' blasts from the speakers. It's just plain rude.

Where animation, sound or video can be a great idea

Animation or video can be a great way to give a 'sit back and watch' presentation of your product or service, but remember people on slower connections and always provide the same information as regular text and images.  

*By animation we mean graphics that move rather than static images. Animation is usually achieved using Flash as it's very smooth, just like watching a movie. But Flash can take a while to download. An older method is to use 'animated GIFs' which are quicker to load but jerky and often annoying.