Now lets suppose due to some catastrophic reason all your company's important data gets lost, then company gets ruined and if proper back-up of this lost data is not there then your company is like a mind-washed individual who doesn't know anything. This important data should be backed-up so that in case of any natural disaster, virus attack or any other problem, the system down-time is as less as possible and normal working of system can be quickly restored.
Various approaches like iterative backup or full backup exist which can be utilized to keep a carbon copy of the done work. The most common approach of data backup is mirroring of the running server. This mirror server is an exact replica of the server and can serve if main server goes down due to any reason. Taking backup of local systems is also important to retrieve important data which can make a difference of life and death of the company.
Generally backup should be taken online on servers having different geographical location as that of the original server, to survive in case of natural disasters also. As is always said prevention is better than cure and in cases where cure is not possible prevention should be the primary and foremost line of defense. One can be cautious regarding security of their important data being transferred online and become prone to attackers but various solutions in form of VPN(Virtual Private Network) do exist which can be used to protect data transmission.