In the early 90s most of the inter-network communications done by Internet protocols such as IMAP, SMTP, HTTP, FTP, LDAP, SNMP and POP was unencrypted. This basically means that even though applications using those protocols used similar authentication methodologies as today (requiring valid UserIDs & Passwords), those critical credential info used to be sent unencrypted over the network. In other words, UserIDs & Passwords used to be sent in plain text format over the network from one system to another.
Since this made it very easy for intruders (bad guys) to crack supposedly secured systems by simply sniffing the network for potential credentials to use, Netscape came up with SSL (Secure Socket Layer v1 & v2, a cryptographic protocol that provides communication security over the Internet Protocol) back in February of 1995. Eventually this solution has evolved into TLS (Transport Layer Security).
OpenSSL is a robust, commercial-grade, fully featured encryption software that implements SSL v2/v3 and TLS v1 protocols. It is developed and maintained by OpenSSL Project and it is widely used by open source communities and even by some commercial systems. If you’re a Linux user of any capacity (either a simple user or a System Admin) you are most likely familiar with OpenSSL, so continue reading.