Cosine Similarity

Cosine similarity measures the angle between two vectors, returning a score between −1 and 1. A score of 1 means the vectors point in the same direction; 0 means they are orthogonal. Because cosine similarity ignores magnitude and focuses on orientation, it is robust to differences in vector length caused by document verbosity. Most vector databases use cosine similarity or inner product as the default distance metric for semantic retrieval.