ESN may refer to: Eastern Security Network, the armed wing of the Indigenous People of Biafra (IPOB) Easton Airport (Maryland), United States Echo state network in computer science Edmonton Street News, a Canadian newspaper Einstein summation notation, used in mathematical physics Electronic serial number for mobile devices Emergency Services Network, in the UK Entertainment Studios Networks, an American cable network Erasmus Student Network, a European student organization European Sensory Network, studies the five senses European Society for Neurochemistry Salvadoran Sign Language