Noise annotations refer to metadata or markers within a dataset that characterize, quantify, or identify the presence, level, or source of error and uncertainty associated with target labels and experimental measurements. In machine learning and scientific data curation, real-world data frequently contain measurement inaccuracies, assay variability, or human labeling discrepancies rather than perfect ground truth. Noise annotations document these imperfections systematically, allowing researchers to gauge data reliability, benchmark algorithm robustness against corrupted or inconsistent targets, and develop learning methods capable of generalizing effectively despite varying degrees of label noise.