There are 3 free services available online that make it easy to compress images and make them more web friendly. They still aren’t anywhere close in terms of advanced options but still good for most people.
What all of the image editors (detailed here) were lacking: a save for the web option. This is something that the paid version of Photoshop has and is very useful and powerful because it takes the image and decreases the file size with very little quality loss.
A 100-kilobytes image or even 1-megabyte image may not seem like anything too bad – especially considering an average computer hard drive can store hundreds of thousands of megabytes. But for the end user on a website, 100-kilobytes will take at least a few seconds to download and display. And if it was a 1-megabyte file size image, then you’re looking at a download time for the end user closer to 10 seconds. That’s not long is it? In the website world, the short answer is YES! Most website visitors won’t wait more than 4-5 seconds for the entire page to load – and if 1 image is taking 10 seconds then you’re in bad shape.
Aside from compressing your image, using images that end in .png will also help as they are usually smaller in file size (although not always).
One of the biggest reasons is that it can have a transparent background, something important to web designers, web developers, and you. Sometimes the background of a website is a color other than white. It could be off-white, gray, or even black. If the background doesn’t match the image then the implementation of the image looks trashy and unprofessional. But PNGs can be transparent, meaning they’ll blend right in. Another reason? Because they tend to have smaller file sizes when compared to JPEGs.