Definition.  Utilization, or implementation, considers the instructional material from the "user's perspective," as Seels and Richey (1994) write (p. 44).  Specifically, utilization considers the conditions, environment, and tools present when the learner is using the instructional materials and working through the knowledge and skills that the instructional designer intends for the learner to learn.  It can include the guidance for the learner, and even assessment of the materials' efficacy. Utilization contains four subdomains:  media utilization, diffusion of innovation, implementation and utilization, and policies and regulations.  

Reflection.  I associate "utilization" with the "implementation" phase of the ADDIE model of instructional design.  For me, this phase is defined by noting, and respecting, different boundaries. The boundaries that exist may be located in the learner characteristics or the instructional context, which may define or limit the types of technologies that are used in the instruction.  The boundaries may also be cultural or legal--both of which are equally important for an instructional designer to respect.  I understand the utilization process as being very tied to much of the information gained through other parts of the instructional design process, including design, development, and evaluation.  It can be challenging to identify and work within boundaries in a situation, but the experiences that I have had through the IDT program have emphasized the importance of respecting these boundaries.  I will certainly carry an awareness of this message into future teaching and learning situations where I will be making important decisions about materials and activities used for learning.