As you can see, authentication in APIs is vitally important. We cannot expose our APIs to the world without guaranteeing at least minimal security, unless the intention is to actually leave it open.
There are many other points to note, such as using Refresh Tokens, external authentication via Facebook, Google and Twitter for example.
About the Author
Diogo Souza works as a Java Developer at PagSeguro and has worked for companies such as Indra Company, Atlantic Institute and Ebix LA. He is also an Android trainer, speaker at events on Java and mobile world.