A "hazard" is something with the potential to cause harm whereas "risk" is the term used to express the likelihood that the harm from a particular hazard is realized and the seriousness of its consequences when realized.

In any activities, hazards can exists in the following aspects:

• Materials or substances to be used
• Machinery, tools etc. to be used
• Energies to be used (e.g. electrical, high pressure etc.)
• People to be involved
• The procedure to be adopted
• The environment in which the activity is to be carried out

By carefully examining each of these aspects, potential hazards can be identified in a more thorough and systematic manner.