ELI5 Sanctions - how exactly do they help?

Why is the word sanction an autoantonym? What does imposing sanctions on another country actually do? How has Cuba been able to live with sanctions for so long? Why do we not have red pistachios in the US? ... we explain like I'm five Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: emmettiow, tasguam, pigakila, comrade_deeco, ozzywalt14, lawlipop83, asus_i7 and ill_outside8827. To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Send us an e-mail: [email protected]