The concept of Sagittal Balance of the Spine, has very recently gained importance and popularity amongst spine surgeons, but also non-surgical therapists such as rehabilitation doctors, rheumatologists, etc. Since the first description in the 80's of the pelvic incidence angle, which is the cornerstone of sagittal balance, a significant amount of work has been done to best describe the concept and allow us to apply it in surgical treatments. Initially, sagittal balance of the spine has helped us understand, in many operated patients, the etiology of “failed back surgery”, but now it is also becoming a valuable tool to avoid mechanical complications and improve the clinical results of thoraco-lumbar spine surgery. However, very often the concept of sagittal balance analysis is very simplistically reduced to the strict matching of lumbar lordosis to the pelvic incidence angle. In this work, I present the different parameters of sagittal balance that need to be studied, and insist on other aspects that truly describe the aim of the concept: pelvic and spinal parameters, harmony of the curves in standing posture, spinal apex, lumbar lordosis distribution, amongst others. The main goal being to plan the fusion surgeries in the best functional way possible and avoid mechanical complications such as junctional kyphosis and junctional failures. Finally, I also present some ongoing research and the latest developments in sagittal balance analysis, for instance the adaptation of fused lumbar spines in the sitting position. A vast and exciting field of research is still ahead.