How to update Samsung smartphone

[Harshiithooda]

Guys from past some days I am seeing some people on member app saying you should update your phone through odin or smart switch 

Please explain how to do it and is it seriously necessary ? 

[iamiceparticle]

https://r2.community.samsung.com/t5/Galaxy-A/Update-via-Smart-Switch/td-p/5144065