Digital mirroless cameras are popular because they offer DSLR-like image quality, handling, and features, while being smaller and lighter system.  Instead of DSLR's optical viewfinders, mirrorless cameras have an electronic viewfinder (EVF) that gives a digital preview of how the image will be recorded by the camera.That is why they can be so compact and light.

The best mirrorless cameras are small, have a tough build and you can use them right out of box. They shoot great, clear photos even in low light. They are able to capture all kinds of highlights and shadows on a single image so you won’t lose the details hiding in the shadows of a shrub or the artful texture of a cloud. Good mirroless camera makers will also promise to support the new options and formats.

Good mirroless cameras are made to be used often. They won't break down easily.

The best mirroeless camera for beginners: Sony a5100 (DSLR quality image sensor, easy to sue)

The second best mirrorless camera for beginners: Olympus E-PL7 (wider lens library, many creative modes)