Any visual web content has weight. And the larger a file's size, the slower it loads. Even a couple of second delay can turn users off your web site. Slowness on the web makes you appear outdated.
Web site sluggishness is also a huge red flag to google. Your slow site will be rejected by google and you will get bad SEO. In other words you won't appear in any google searches.
Say for example you are an excellent mechanic who specializes only in classic car restoration. As there are not many people in this specific niche you would expect to pop up instantly on page 1 of a google search if someone typed in “classic car restoration”.
And if people went to your site they would immediately hire you! As your homepage has rave customer reviews and endless photos of your beautiful work. However some fool built your web site and all the images are enormous. So your site loads clunkily.
Which makes it look badly built to google. For Google is the self imposed standard police of the web and seeks excellence from the web sites it patrols.
Everything needs to be instant for google to approve. Google is unimpressed with your huge images and so sends you to the wasteland beyond page 3 of a google search... ever looked that far? No, no one has.
Happily though it's easy to sort this out with your photos. You can scale down the physical dimension and the picture's pixel quality quickly in photoshop.
To explain what this means let's imagine you got a professional photographer to take a photo of your best restored car. The image would be 300 dpi – which means “dots per inch”. The more dots in an inch the richer the image. If you want to physically print a photograph of your car to blow up and hang on the wall of your workshop, you want this print quality at 300dpi.
For video files it's not so simple. But I will show you my tricks in part 2!