Over 60% of searches happen on mobile phones. Google prioritizes how sites work on mobile.
If your site doesn't work on phones, you lose most of your potential customers.
Common issues: Not responsive, buttons too small, text too small, slow on mobile, images overflow, form inputs too close.
How to fix: Implement responsive design, make buttons minimum 48x48 pixels, increase text size to 16px minimum, optimize for mobile networks.