When we want to transmit any data containing confidential information (including logins and passwords), we should always use an encrypted connection. This way we avoid a situation where the data is read by outsiders. SSL certificates have a dual functionality:

• encryption of data transfer between server and client
• the ability to verify the server's identity

Certificates available on the market can be divided into:

• SSL DV (Domain Validation) - identifies only the identity of the domain
• SSL OV (Organization Validation) - identifies the identity of the domain as well as the domain owner (ownership of the domain)
• SSL EV (Extended Validation) - identifies the identity of the domain, its owner, and additionally verifies the business entity and the company's address (green bar in the browser)

In the case of SSL DV certificates, the verification process is limited to receiving a message at the address proposed by the certificate authority. For the other two, the requirements are already greater, e.g. sending various documents confirming our personal data or company data.

You can generate an SSL certificate yourself; the downside of this solution will be an annoying message about an untrusted certificate provider. I'll list three solutions that will help you get rid of the above-mentioned message:

• Manually installing the certificate as trusted in the system/browser.
• Using the offer of companies offering various types of certificates for a fee (annual fee).
• Using the free offer from StartSSL

The first solution basically only works for a small number of users who trust us to install the certificate on their system.
The second solution is paid certificates... and in my humble opinion, this is only useful for broadly defined e-commerce.
And finally, free SSL certificates. There are two entities on the market offering free certificates: StartSSL and CAcert.org.
CAcert is a community Certificate Authority that issues certificates to the general public for free, using a method of authenticating people called the web of trust. Unfortunately, certificates from CAcert are not honored (trusted) by popular browsers.
StartSSL, an Israeli SSL certificate issuer, offers free SSL DV certificates, certificates for securing email as well as encrypting documents. StartSSL is currently the only company offering certificates that are recognized by all popular browsers.

Registering on the StartSSL website:

• Go to: StartSSL
• Click Sign-up, and register providing real data.
• Get the email with the password. Following the instructions, you'll install the certificate in your browser.
• From now on, we log in without a password.
• Just in case, I recommend making a backup of the certificate.

Domain validation:

• The first thing is domain verification: Validations Wizard -> Domain Name Validation
• We provide the domain we're going to secure.
• At this step we can choose one of several email addresses (postmaster/hostmaster/webmaster@our_domain) to which the verification code will be sent.
• After successful domain verification, all that's left is to create the certificate and install it on the web server.

I'll describe the process of creating and then installing the SSL certificate in a separate article: StartSSL certificates - generation and installation on an nginx server.