In the Photos app on your iPad and iPhone (as well as the Mac), you have four views of your library: Years, Months, Days, and All Photos. For the first three, the Photos app doesn’t show all your photos, and instead, it picks representative images that may not include any particular shot you’re looking for. The All Photos view shows everything, but this also means it can be overwhelming. To help with this, you can navigate All Photos more easily by pinching in to shrink the thumbnails and then pinching out to make them larger again. At the largest size, a single photo takes up the entire width of the screen. This way, you can pinch to zoom out and get an overview of all your photos; when you are ready to dig in and view the photos in more detail, you just pinch to zoom in.