Lung segments are the component units of the lung lobes, and each lung lobe is composed of different lung segments. Each lung segment has corresponding segmental bronchi and blood vessels. Each segmental bronchus is a branch of a lobe bronchus, and each segmental bronchus, its branches, and the lung tissue to which it belongs together constitute a lung segment. Each segment is wedge-shaped, with the base on the surface of the lung and the tip at the root. Segmental lung resection: a surgical procedure for early-stage lung cancer. Its long-term efficacy in treating early-stage lung cancer is equivalent to that of traditional lobectomy, while preserving more normal lung tissue. This procedure is more suitable for hairy glass lesions or lung nodules smaller than 50px. Of course, the location of the lesion is also important, as it should be centered in the lung segment or as far away from the adjacent lung segment as possible to ensure clean resection margins. Segmental lung resection is generally more difficult than normal lobectomy because of the need for more detailed dissection of the hilar vessels and bronchial structures. Thoracoscopic views that are magnified and exceed the resolution of the human eye are more conducive to the dissection and resection of lung segments. It is important to note and emphasize that segmental lung resection is not a non-anatomic wedge or partial resection of the lung. Wedge or local excision does not involve the dissection of the blood vessels and bronchi of the lung segment to remove the possible root drainage of the tumor. Extensive clinical data show that wedge or local resection has a higher recurrence rate and a significantly worse survival rate than segmental or lobectomy. Commonly performed segmental lung resections are: dorsal segmental resection of the lower lobes of the right and left lungs, trisegmental resection of the left intrinsic upper lobe, left lingual segmental resection, post-apical segmental resection of the right upper lobe and basal segmental resection of the right and left lower lobes. Thoracoscopic segmental lung resection allows for less invasive surgery and is a good surgical alternative for patients with early stage lung cancer but with poor lung function in advanced age.