Responsiveness
To create a grid, you typically set parameters like total width, number and width of columns, gutters, and margins:
Sketch and Photoshop’s grid controls
This creates a grid scaffold that is drawn as a set of guide lines on top of the artboard. Elements can then be manually snapped to these guide lines:
Print-legacy grids: in existing tools, grids are just visual guide lines to which elements can be snapped.
This works fine for print. The designer knows that their publication is going to use, say, the A4 paper size. But what happens in digital, when you need to simulate a different device size? Changing the artboard dimensions means that the grid either is either too big or too small:
No responsiveness: resizing the artboard in existing tools doesn’t resize the grid.
The most common workaround to this problem is to create multiple artboards, each corresponding to a unique device category, like smartphones, tablets, and desktops. Individual grids can then be created separately for each device/artboard:
Simulating responsive: creating grids for a few different device sizes can help, but details still fall through.
This is a pretty lousy simulation of output media, though, as it only represents three potential device resolutions. (In the above example, it’s the iPhone 7, the iPad, and a 13″ Macbook Pro.) Are the grid decisions still sound on a Google Pixel or an iMac 5K? What about in landscape orientations or split views?
Working with only few fixed grid configurations makes it easy to miss problems while you’re working. Either the developer will find them during implementation — necessitating a lot of annoying back-and-forth — or the broken layouts will end up in your final product.