The study is 3 arms observational study with no intervention that aims to understand the link between Crohn's disease, microbiome and diet in children. 150 children newly diagnosed with Crohn's disease will participate in the study and their data will be used to create an algorithm about their microbiome, disease, diet, etc. 100 other children newly diagnosed will participate in the study and their data will be use to validate the algorithm. The investigators will be recruiting 50 healthy participants: 20 that are undergoing an endoscopy for abdominal pain and 30 that comes to the physician for different reasons. After parental consent, the participants will receive an explanation of the study and sign a consent form for colonoscopy. Before colonoscopy, participants will bring fecal samples, give blood samples, biopsies and biopsy brushes (superficial scraping of the tissue) will be taken during the operation. These samples will be retained until further consent is obtained for further study. After receiving the results of the colonoscopy, children who have been diagnosed with Crohn's disease will be offered to participate in the second part of the study, they will receive an explanation about the app, collection of fecal samples at home, diet logs and anthropometric measurements, demographic information, medical and family history will be registered. During the first 3 months: the participants will be asked to log data in the app and collect fecal samples at home. They will be asked to come for a follow up visit where anthropomorphic measurements and blood samples will be taken. Participants will be asked to log in every day to report in the app daily activity and food intake throughout the study period. Each week, the research coordinator will call on participants to make sure the app is correctly filled in, collect the stool samples correctly and answer questions. During the entire study participants will collect fecal samples, every first week of the month participants will enter information in the app. For children who have not been diagnosed with Crohn's disease by the colonoscopy, or children who visit the institute for reasons other than inflammatory bowel disease without a clear finding will participate in the study control group. If consent is given, fecal samples will be collected at the entrance of the study and after one year, blood samples, a food questionnaire and anthropometric indices, demographic information, medical and family history will be completed.