This document discusses Apache Arrow, a new open source project that aims to standardize in-memory columnar data representations. It will enable faster data sharing and analysis across systems by avoiding costly serialization. The document outlines how Arrow focuses on CPU efficiency through cache locality, vectorized operations, and minimal overhead. It provides examples of how Arrow could improve I/O performance for Python tools interacting with big data systems and the Feather file format developed using Arrow. Language bindings for Arrow are under development for Python, R, Java and other languages.