A digital certificate is a digital document that verifies the identity of a person or organization, and provides information about where the certificate was issued and when it expires.
But those are some big, big words.
Put simply, a digital certificate is a token file that tells you who someone is. Think of it like a passport, but for the internet.
Digital certificates are only valid if issued by recognized certification authorities. You'll need them if you want to prove your identity as an individual or as an organization online – to show the world you are who you say you are so that others can trust you.
What is a digital certificate used for? Well, they allow companies and persons alike to conduct business safely and securely, knowing that they're interacting with someone whose identity is verified, and not some impostor trying to steal their data or money.
So, yes, digital certificates are important.
In Brazil, digital certificates are regulated by law, and are a requirement for companies conducting business online. They work through cryptographed unique keys, producing a private token for the authorized person and a public decrypting token to be shared with those verifying their identity.
Company founders need to apply for digital certificates as individuals and as their legal entity, with an authority recognized by the local government. Certificates are used to access the country's Nota Fiscal systems, and to generally transact online when interacting with governmental institutions.
How long can digital certificates be valid? All digital certificates have expiration dates varying from 12 months to 36 months after the date of emission.
Certificates for individuals are known as e-CPFs, referring to the Register of Individuals (Cadastro de Pessoa Física), while the ones for companies are called e-CNPJs after the National Register of Legal Entities (Cadastro Nacional de Pessoas Jurídicas).
If you're starting a company with a legal entity in Brazil, the answer is 'yes you do'. You'll need an e-CNPJ to be able to invoice customers, and an e-CPF to transact as a shareholder and/or administrator on behalf of your company.
In case you need to go out and get one on your own, make sure to find a service provider that is accredited by the government – googling "Digital certificate {name of your city}" should help you find one.