How do I decrease a pic file size for a website?

First should I use .jpg .gif and can I use .png? How do I change the file size of say a 1 mg pic to something more reasonable for a site?How do I decrease a pic file size for a website?
.gif is good for text, gradients and images w/ less than 256 colors



.jpg is good for pictures



.png 8 functions similar to .gif

.png 24 is the best but it doesn't always compress to a really small size. It also offers alpha transparency (varying levels of transparency).



If you have photoshop use the save optimized for web features and you can scale jpgs down to about 60% with no real loss in quality.



If you don't have photoshop use a free tool like gimp, it's the next best thing: http://www.gimp.org/



See this guide for more info on the types of compression and the pros and cons of diff file types. The important thing to understand is the difference between lossless and lossy compression...



http://www.ou.edu/class/digitalmedia/artHow do I decrease a pic file size for a website?
You need to resize the pic