Responsive web design has become more crucial than ever with the increasing variety of devices used to access the internet. Understanding core principles is essential for modern web developers.

Mobile-first design approach continues to be the standard, ensuring websites work perfectly on smaller screens before being adapted for larger displays.

CSS Grid and Flexbox have revolutionized how we create responsive layouts, making it easier to build complex designs that adapt seamlessly to different screen sizes.

Performance considerations in responsive design include optimizing images, implementing lazy loading, and ensuring fast load times across all devices.