There are two main types of bag available to buy for your camera, those made by the camera manufacturer themselves to fit their cameras and those made by independent bag manufacturers to fit varying sizes of camera.
You usually find that the camera manufacturers bags/cases are often only designed to cover the camera itself to protect from scratching and do not have any padding, pockets, straps etc. This makes them lightweight and stylish and great for days out and parties. However when it comes to going on holiday, you often find the need to take spare batteries, cards, cables and chargers so need something with more padding for travelling and more pockets for storage. This is where independents like Billinham and Lowepro play a major role. They all sell some great bags made in lightweight material in a wide range of colours and styles, so there is bound to be something to suit you.
Billingham construct their bags from canvas, leather and metal fittings, traditionally styled.
Lowepro make an extensive range of bags, some of which are floatable and waterproof, there are also hard cases which protect equipment from the most extreme of conditions and can even be floated down rivers!!! These hard cases are made by Pelican and other manufacturers.
There are also underwater specialised cases to enable you to take your precious camera underwater in the sea and rivers - these are made by Ewa Marine and others, and range from models for deep sea use to simple small cases designed to protect your small compact camera from sea sand and sea water spray.
Sometimes it is a good idea to have more than one case, particularly if you are keen on taking your camera out for different occasions - you may wish to protect your equipment in the likes of a Pelican Case while travelling on a safari or by train / plane, and when you arrive at your destination you might want to use a soft bag or a soft rucksack to tote the equipment.
Cheap bags are generally not as well constructed or user friendly as the dedicated big name camera bags - if you buy a Billingham or a Lowepro, you know you are buying a brand which is noted for quality and the manufacturers specialise in making camera cases. That is not to say that you cannot construct bags with protection that you have added, for odd shaped pieces of equipment by using general kit bags sold in high street shops and markets. Foam inserts and cut-to-shape protection can be inserted in this type of bag as well. However, generally you are far better off with a bag designed to keep your precious investment safe and secure. Some of these cases are even tested by floating them down rivers or throwing them into gullies or onto rocks!! The investment of such a case will be well worth it if your camera case happened to fall in a river while you were on holiday and it was waterproof and your equipment was rescued without any damage..........
Bags often outlast their initial equipment - they can serve a photographer well over a lifetime of use.