SEA is defined as:
a systematic process for evaluating the environmental consequences of proposed policy, plan or program (PPP) initiatives in order to ensure they are fully included and appropriately addressed at the earliest appropriate stage of decision-making on par with economic and social considerations(Sadler and Verheem, 1996)
SEA is a tool developed for assessing the impacts that may be incurred through the implementation of plans, programmes and higher-level policy decisions. This means that an SEA occurs over a longer period, and at a greater scale than EIA: an SEA is typically applied to an entire sector or geographical area.
The key point is that decisions are assessed at an early stage in respect of their potential environmental impacts, enabling alternative options to be assessed more easily.