# Plain and Simple: IndexFlatL2

Given a set of vectors, we can index them using Faiss — then using another vector (the query vector), we search for the most similar vectors within the index. Now, Faiss not only allows us to build an index and search — but it also speeds up search times to ludicrous performance levels.

IndexFlatL2 measures the L2 (or Euclidean) distance between all given points between our query vector, and the vectors loaded into the index. It’s simple, very accurate, but not too fast.

Image credit: pinecone.io