image resolution for websites

[unwashed potato!]

I have seen people say this before on this forum but never paid much attention to it, and now i want to know

What resolution should images be to make them loko the best? Im guessing the bigger the better but obviously there must be a size that when it gets that big, its not going to get any clearer

Thanks

 

[unwashed potato!]

well say for like like the logos and any other graphic stuff on a site? What sort of resolution should i be designed in?