Malware is malicious software which has been developed by someone (or some organisation) to cause disruption or, more commonly now, to earn them money. Your money. It wasn't always this way. Originally, computer viruses were created by computer enthusiasts almost as a game to see how many PCs they could infect.
Several companies have launched apps which give full access to smartphones or computers, allowing snoopers to see text messages, emails and photographs, listen to phone calls and even activate phones to listen to sounds around the handset even when it is not in use.