Any surgeon providing care to patients with congenital, oncologic, infectious, or traumatic processes impacting the head and neck should have an intimate knowledge of the local anatomy. The complex fascial system in this region results in a series of loosely and tightly bound spaces that can both harbor and/or facilitate the rapid spread of infections through these fascial planes and potential spaces. Deep neck space infections may occur spontaneously from cutaneous, lymphatic, odontogenic, otologic, salivary gland, sinus, and hematogenous sources or develop as the result of surgical/iatrogenic manipulation. These infections are typically polymicrobial, involving a mixture of Gram-positive cocci, Gram-negative rods, and beta-lactam-resistant anaerobes commonly found in the oropharyngeal flora. Other populations, such as immunocompromised or hospitalized patients, are particularly vulnerable to infection by certain opportunistic and antibiotic-resistant pathogens. Understanding the deep neck anatomy is crucial for predicting the spread of infection and guiding treatment strategies. The superficial and deep cervical fascial planes form a series of compartments and spaces including the retropharyngeal, danger, prevertebral, carotid, parapharyngeal, submandibular, sublingual, parotid, masticator, temporal, and infrahyoid spaces. Despite their rarity in the post-antibiotic era, deep neck space infections pose a significant threat as they progress rapidly and can quickly lead to life-threatening complications. Delayed clinical presentation is common due to the compartmentalization by fascial planes, therefore early recognition requires a high index of suspicion, thorough clinical examination, and diagnostic imaging studies, typically contrast-enhanced computed tomography (CECT). Treatment requires a multidisciplinary approach, including advanced airway management, administration of empirical broad-spectrum antibiotics, and surgical drainage when indicated. This review provides a comprehensive overview of deep neck space anatomy and its defining fascial planes, as well as discussions on epidemiology, specific microbiology, clinical presentation, diagnosis, antibiotic selection, and surgical treatment options.