# What is an Inner Product?

An inner product is a mathematical operation that takes two vectors of the same size and produces a scalar value. It is calculated by multiplying each element of one vector with the corresponding element of the other vector and then summing up the results.

It is used in many areas of mathematics, including linear algebra, calculus, and geometry. In machine learning and data science, inner products are used to measure the similarity between two vectors.

For example, in a neural network, the inner product of two vectors can be used to measure the similarity between two input vectors, or between an input vector and a weight vector.

Inner products can also be used to measure the similarity between two images, or between two text documents.

Next Chapter:

What is Cosine Similarity?