Although there are several conventions dealing with corruption and bribery, there is no single globally accepted definition of corruption and bribery.
Corruption is defined by Transparency International, the leading international NGO in fighting corruption, as 'the abuse of entrusted power for personal gain.'
Corruption can also be differentiated in terms of what can be called 'true corrupt intent' and 'necessary corruption', which occurs in order to get things done. Corruption in terms of true corrupt intent implies bribery in order to obtain a service to which one is not legally entitled. In contrast, necessary corruption implies bribery in order to obtain a service to which one is legally entitled. Facilitation payments would fall under this latter category of corruption.
The main forms of corruption are bribery, embezzlement, fraud and extortion.
Corruption is traditionally defined as a practice involving a public official abusing her/his position. However, corrupt practices can also occur within the private sector when a private sector employee abuses of her/his position in the private entity for personal gain. Private (also called commercial) bribery is only addressed by a limited number of international conventions.
You can find an extensive list of corruption definitions in our Corruption Vocabulary.