This document discusses various types of recommendation systems and assumptions made in developing recommendations. It describes personalized and non-personalized recommendations, which can be user-interaction driven through passive or active feedback, editorially curated, or based on statistics. It also discusses factors that can influence recommendations like similarity, correlations, user activity, sensors, and external influences like mood, time, empathy and induced preferences. It raises questions about using relationships between content, expressing different interest levels, and optimizing the amount of content information presented based on interest, time and mood.