Whether you use Lightroom Classic, Lightroom 6 or the cloud-based Lightroom, sometimes you’ll want to view photos from more than source together in the grid, whether the sources are folders, dates, collections or albums. It’s easy – select the ones you want using the selection methods that work for files, and then the images for all will show in the grid. To select multiple folders or other sources that  are next to each other, click on the first, then Shift-click on the last. If they aren’t next to each other, click on the first, then Cmd/Ctl-click on each additional one. You can also have a mix of sources – select a folder and a collection, for example.