Gap analysis is a technique for comparing the current state of the business ('As Is') with the desired future state ('To Be') to identify what is missing and what needs to change. The logical first step is to establish the current starting point. Therefore, the process begins by:
Assemble representations of existing situation (The 'As Is' model). This involves investigating and documenting the current processes, organisation, people, information, and technology (POPIT).
Assemble representations of target or desired situation (The 'To Be' model).
Identify gaps to be addressed (The difference between As Is and To Be).
Consider possible actions to address the gaps (Developing the recommendations).
(Reference: BCS Business Analysis Practice - Gap Analysis)