Compressing images is vital if you want your website to run quickly. There are several tools, both standalone programs and web apps, that can quickly reduce the size of your files, but Compressor.io is our absolute favourite.
The tool is extremely easy to use. Select a compression mode (lossy for all images or lossless for JPG and PNG files), drop your file into the browser window, wait for the file to upload, and have it compressed in the blink of an eye. Compressor.io uses powerful alogirthms to make the size of your files significatly smaller, allowing you to save hundreds of kilobytes without noticeable quality loss.
Once your compressed image is ready, you can download it to your computer or send to Google Drive or Dropbox. There's also a handy visual comparison tool, which lets you see the quality difference (or lack thereof) between the original and compressed picture.