Graded browser support: the ultimate method
Firstly you need to choose which browsers you will be supporting. As a general guideline, you should always support the big 3: Internet Explorer, Chrome and Firefox. If you are diligent and would like to do it thoroughly you will have to add the perpetual runner-ups—Opera and Safari—to the equation. That's the easy part.
Now you have to select which versions of these you should support. There are 3 grades:
- Base is plain and simple what you should start with: if it doesn't work flawlessly or degrades poorly in these you are not on the right track.
- Minimal represents the versions which should ideally be supported too but most of the time are overlooked. For these you can provide a reduced experience without all the bells and whistles using graceful degradation and progressive enhancement but the essential functions like navigation and content access remain a must.
- Extreme should be be taken into account in the unlikely case that you are handling a very high traffic website: if it's not on this list you can neglect that grade entirely.