Cerebrospinal fluid (CSF), a transparent, colorless bodily fluid, is present around the brain and spinal cord. The ventricular system and subarachnoid space are occupied by CSF. Specialized ependymal cells in the choroid plexus of the brain's ventricles produce CSF, which is then absorbed in arachnoid granulations. About 150 mL of CSF are present at any given moment, and 500 mL are produced daily. The CSF protects the brain inside the skull mechanically and immunologically. The cerebral autoregulation of cerebral blood flow is another essential role played by CSF. The imbalance between the production/secretion/absorption cycle or obstruction could lead to hydrocephalus. In this book, we will discuss the essential pieces of information related to CSF (i.e., anatomy, physiology) and describe CSF-related pathologies (i.e., hydrocephalus and infections) and their mechanisms. We will also discuss the latest advancement in the treatment strategies of hydrocephalus. Diagnosis and treatment strategies for CSF infections will also be covered in this project.