A Flash-based website is one that uses Flash as its core platform.
Pros
- When done properly, Flash can look very cool.
Cons
- If the entire website is built in Flash, its not good for SEO (search engine optimization)
- Flash is expensive to produce (a lot of extra graphic design work, a lot more custom programming and testing, etc)
- Flash is expensive to maintain
- A significant number of people do not like lots of movement and sound.
Alternatives
- Build a hybrid website with some Flash elements (meaning Flash banners)
- Figure out what effect you want and build it using JQuery or another programming language
- Avoid it altogether because it's far more of pain for most companies than it's worth