Depends on what the image is. GIF is good for images with large blocks of similar colours. It also supports transparency. JPEG is good for photographic images. PNG is similar to GIF, but better. But transparency isn't supported by ancient browsers (IE6 etc) http://www.w3.org/QA/Tips/png-gif http://www.killersites.com/articles_2005/theory/images-in-webpages.php
Cheers for that, most of my pics have been saved as png so might aswell stick to it, but jpeg will do for photos
GIF has bad quality and I kinda hate it. I like PNG much more. Good quality, transparency, I always use PNG.
i always use PNG, support transparency and much better color than GIF. and use JPG for Photo. make the photo size smaller.
PNG are often much larger than GIFs as well - not all gifs are bad. Learn image optimization and learn what to use for the circumstance you're optimizing for.
You really want to stick to using .png or .jpg - gif I rarely ever work with unless I have a compression issue. Generically avoid gif.
It really depends on what you need, gif,png and jpg each has their own strengths. gif is good if you are dealing with only a few colors with no transparency as this has a small filesize. jpg works best on images that has multiple colors and big dimensions but has no transparency (ie photographs). png has transparency and is better in blending than gif but cannot do animation and it has a bigger file size than gif.
as everybody has stated .gif, .jpg and .png and widely accepted on most browsers (apart from IE9 beta because lets face it microsoft are idiots) and chrome has some issues with some .gifs but those 3 are the most popular and i would suggest you stick to them =)