Image optimisation is a tale of two halves, the first being focused around ensuring the image is compressed as much as possible without loss of quality. This allows the image file size to be decreased, and therefore load quickly. You should also make sure that you’re serving images which are scaled correctly.The second half is ensuring that images have appropriate file names and alt text. For example, an image with a file name of ‘IMAGE1.PNG’ and an alt text of ‘IMAGE1’ isn’t useful for search engines, nor people using accessibility software. The filename and alt text should accurately describe the contents of the image – for example, ‘red-car.png’ and ‘red car on a road’.