Corruption is the abuse of entrusted power for private gain. This is how corruption is defined in the strategy drawn up by the anti-corruption cooperation network. Corruption can be defined in a number of ways, but norm-breaching actions and pursuit of some kind of advantage are mentioned in most definitions.
The advantage being pursued through corruption is usually undue, meaning that the person pursuing it is not entitled to it. The advantage may come in a variety of forms, and it often improves the position of its recipient, at least momentarily. The advantage is not time-bound: it can be received well before the abuse of entrusted power or considerably after it.
Drawing the line between beneficial networking and condemnable corruption is often difficult. Circumstances, the position of the persons involved, and the nature of the advantage, among other things, affect the overall assessment of the case. The court is the instance that eventually draws the line between criminal and non-criminal activities.
It is, however, always beneficial to assess one's own actions and how they may seem from outside. You could, for example, ask yourself: if media would like to investigate the case and publish an article of it, could this jeopardise the credibility of some person or organisation? Activities may be ethically questionable even if they do not constitute an actual criminal offence.