For more information regarding Bristol-Myers Squibb Clinical Trial participation, please visit www.BMSStudyConnect.com Inclusion Criteria: - Adult participants (at least 18 years of age at time of treatment decision) - Diagnosis of Squamous cell carcinoma of the head and neck (SCCHN) and participants are progressing on or after platinum-based therapy, administered for locally advanced, metastatic or recurrent disease (Cohort 2: prior platinum-based therapy was administered for locally advanced disease in the adjuvant or primary setting, e.g. radiotherapy) - Diagnosis of SCCHN has been confirmed by histology or cytology (either at initial diagnosis or any time later during the course of the disease) - Treatment decision to initiate a treatment with nivolumab for the first time for the treatment of SCCHN (according to the label approved in Germany) has already been taken Exclusion Criteria: - Current primary diagnosis of a cancer other than SCCHN, ie, a cancer other than SCCHN or cancer of unknown primary (CUP-syndrome) that requires systemic or other treatment, or has not been treated curatively (as per discretion of the investigator) - Previously treated with nivolumab and/or ipilimumab, an anti-PD-1, anti-programmed death ligand 1 (anti-PD-L1), anti-PD-L2, anti-CTLA-4 antibody, or any other antibody or drug specifically targeting T-cell co-stimulation or immune checkpoint pathways (applicable for any indication) - Currently included in an interventional clinical trial for their SCCHN. Participants who have completed their participation in an interventional trial; or who are not receiving study drug anymore and who are only followed-up for Overall survival (OS) can be enrolled