Vandals often use hacking techniques to deface a website or destroy data and files, but there are also those who just want to steal resources (make use of other peoples' servers without their knowledge or permission) or to cover their tracks by stealthily making use of hardware owned by legitimate businesses to carry out processing for illegal operations or to relay spam and viruses to others.
The best defense against the majority of these types of attacks comes through installing and maintaining the latest versions of anti-virus and firewall software. As new threats are identified, updates are issued which can identify and neutralize most harmful operations before they have a chance to do any damage. Having a server fully managed by a reputable hosting company ensures that these defenses are always in place.
Perhaps a more sinister threat is that of 'black hat' hackers, or 'crackers'. As a general definition, 'white hat' hackers are enthusiasts who enjoy learning the intricacies (including weaknesses) of computer systems with no malicious intent, whereas 'black hat' hackers are those whose sole purpose is to break into systems and gain access to information and functions to which they are not entitled. The word 'hacker' was originally used to refer to the 'white hat' variety, whereas 'cracker' was used to identify 'black hats'. The media have since latched onto the word 'hacker' almost exclusively in connection with 'black hat' hacking, and this is usually what is understood by the term 'hacking' today.