One of the other threads in the Web Page Design-Coding Forum is Web Page Alignment, where the person was seeking advice about his web-page, a 4-h club site
When I went to the 4-H link for the first time, I immediately noted how fast the 1st picture loaded, then how slow the 2nd picture loaded. I found that the first picture is a natural 401-W by 301-H (pixels) image file. However, the 2nd picture is a 1600-W by 1200-W (pixels) image file. To make the 2nd picture fit neatly withing the web-page's margins, the author used a standard HTML protocol to reduce the image pixel dimensions to 401-W by 301-H.
There's nothing really wrong here, in so far as the reduction technique helps make the picture display nicely. But the reality is this - It's still the same large image file of 1600x1200 pixels. Because it's larger than the smaller 1st image file, the 2nd file takes longer to download. Also, the 2nd file's longer download time translates into usage of valuable bandwidth allotment.
If you plan on making a web-site, where SEVERAL very large image files will be used for displays, you will chew up bandwidth allotment very quickly, making the site costlier to maintain.
The solution - Do not use an HTML protocol. Instead, get an image file viewing program that creates re-sized copies of your original image files.
I use an image viewer called Irfanview. It has the resize image feature. It gives you 2 options: (1) Re-Size by altering specific width and/or height information. .. (2) Re-Size by percentage of original.
Please note this - Irfanview's "Save" and "Save As" options are different from other programs. "Save" saves to an external program or device. "Save As" is waht saves your file as a file. When saving, be careful of the file type (BMP GIF JPG) you want, plus use a filename different from the original.