Selecting multiple images is really easy, if you have ever selected multiple items in Finder it's exactly the same process.
You will know a photo is selected because it has a blue border around it.
You can do any of the following:
- To select a single image, click it.
- To select several images located together, drag around the images to enclose them within the selection rectangle.
- To select a group of images located next to one another, click the first image, then hold down the Shift key while you click the last image.
- To select multiple images that are not adjacent to one another, hold down the Command key while you click each image.
- To select all images in the gallery, press Command-A or choose Edit > Select All.
- To deselect specific images in a group of selected images, hold down the Command key and click the images you want to deselect.
- To deselect all images, click outside a photo.