Introduction:
Smartphone use has become a common behavior that can lead to physical and mental strain. Body posture while using a smartphone often promotes excessive neck flexion, torso and chest tilt, and unfavorable changes in pelvic position. The authors believe that it is necessary to present clear, practical guidelines for maintaining an ergonomic body posture in various positions throughout the day.

Aim:
To present optimal ways of using a smartphone with health-promoting recommendations that result from an analysis of body position geometry.

Material and methods:
A scoping review of the literature using ScienceDirect, Taylor & Francis, PubMed, EBSCO, Ovid LWW, and Springer databases was conducted using the keywords ‘smartphone,’ ‘posture,’ ‘spine alignment,’ ‘head tilt,’ ‘smartphone addiction scale,’ ‘spinal overload,’ ‘kyphosis,’ and ‘lordosis;’ as well as ‘Euclidean geometry.’ Articles published after 1995 were included. The analysis was supplemented by the authors' over 40 years of clinical experience

Results and discussion:
Body posture analysis using the principles of Euclidean geometry clearly identified desired behaviors while using a smartphone. It was demonstrated that even small angular changes in the sternum and the sacrum can significantly impact the proportions of individual body segments, including the head, and consequently reduce musculoskeletal overloads.

Conclusions:
(1) The assumptions of Euclidean geometry provide a good justification for explaining health-promoting behaviors when using smartphones. (2) Postural education – based on understandable geometric patterns – should be an integral element of behavioral and preventive health care proposals for the smartphone-using population. (3) Individualized implementation of health-promoting habits is recommended, which increases the effectiveness and sustainability of the effects.