Inclusion Criteria:  No history of benign and malignant tumors (including carcinoma and adenoma) of upper GI (including esophagus, stomach and duodenum)  Exclusion Criteria:  Subjects that cannot stand the gastroscopy procedure or cannot cooperate with endoscopists Emergency endoscopy and therapeutic endoscopy Subjects with history of esophageal or stomach surgery or endoscopic surgery Pregnant Subjects that refuse to cooperate with data collection or sign the informed consent