In summary, this thesis has discussed in detail the features of Major depressive disorder and its various means of treatment. Depression is a common disease and can be deadly if left untreated. It can be easily overlooked or ignored, especially in the most vulnerable populations like the elderly and pregnant women. Treatment of MDD can be pharmacotherapy, psychotherapy, or a combination of the two. In the case of treatment-resistant depression, somatic therapies like ECT, TMS or vagal nerve stimulation. Pharmacotherapy can be divided into the typical and atypical, the most widely prescribed antidepressants are SSRIs due to their relative safety and tolerability. Most antidepressant’s mechanism of action is on the serotonergic, norepinephrine, and dopaminergic systems. Psychotherapy usually used for MDD is CBT, which tackles cognitive distortions, and IPT which targets interpersonal relationships. Alternative forms of therapy such as exercise and dietary supplements like folic acid can augment pharmacotherapy use. Treatment of MDD requires selecting the right choice for the patient according to the patients’ comorbidities, preferences, and chances of adhering to treatment.