Flip-out screens can be useful for tricky shots.
The device is protected with extra seals to prevent failures caused by dust, raindrops, and water splashes.
The device is dustproof and water-resistant. Water-resistant devices can resist the penetration of water, such as powerful water jets, but not being submerged into water.
We consider a lower weight better because lighter devices are more comfortable to carry. A lower weight is also an advantage for home appliances, as it makes transportation easier, and for many other types of products.
An optical viewfinder (or OVF) allows the photographer to compose a shot while seeing exactly what the lens will capture. OVFs have no time lag and require no power - as opposed to electronic viewfinders, which can drain battery life. OVFs are also better in low light situations.
A hot shoe can be used to attach an external flash, as well as light meters, viewfinders, rangefinders and other attachments.