The following are the three learning domains, into which learning objectives are categorized.

Cognitive domain focuses on the thinking abilities, intellectual skills, or cognitive skills (Krathwohl, 2002). For example: Define terms, analyze a concept, write codes, or create a 3-day camping trip plan.
Affective domain focuses on emotions, feelings, choices, attitudes, values, willingness, etc. (Krathwohl et al., 1956). For example: Value ethical and legal practices, appreciate individual differences, or choose safety as priority when driving.
Psychomotor domain addresses motor activities (Harrow, 1972). For example: Operate an equipment, shoot an arrow, or walk on the rope.

Learning objectives fall under one or more of the three domains. The affective domain has received much less attention in educational settings when the cognitive domain has become the main (perhaps sole) focus in preparing students for future careers, which soft skills (e.g., communication, teamwork, enthusiasm, attitude, and other interpersonal skills) are highly sought out by employers (Majid, Liming, Tong, & Raihana, 2012; Schulz, 2008). Learning objectives should include learning in all three domains for more holistic learning (see example here).

We will begin discussing the cognitive domain.

References

Harrow, A. J. (1972). A taxonomy of the psychomotor domain. New York: David McKay Company.
Krathwohl, D. R. (2002). A revision of Bloom's taxonomy: An overview. Theory into Practice, 41(4), 212-264.
Krathwohl, D. R., Bloom, B. S., & Masia, B. B. (1956). Taxonomy of Educational Objectives: The Classification of Educational Goals. Handbook II: Affective Domain. New York: David McKay Company.
Majid, S., Liming, Z., Tong, S., & Raihana, S. (2012). Importance of soft skills for education and career success. International Journal for Cross-Disciplinary Subjects in Education, 2(2), 1036-1042.
Schulz, B. (2008). The importance of soft skills: Education beyond academic knowledge. Journal of Language and Communication, 2(1), 146-156.