Welcome to Oracle Cloud Infrastructure (aka OCI) - one of two pillars of Oracle Cloud and really of Oracle Corporation. Oracle Cloud Applications is the second pillar - a broad suite of SaaS applications that support business processes in virtually all industries and regions. Oracle Cloud Infrastructure provides the foundation for Oracle Cloud Application - a platform for running enterprise applications with services such as database, security, API management, (serverless) compute, networking and end-to-end monitoring. These services that Oracle leverages for Oracle Cloud Applications are also available to anyone else. From more than 20 regions (data centers) around the globe, OCI services can be consumed by any organization.
Oracle Cloud Infrastructure is sometimes referred to as Gen2 Cloud, because OCI is the second generation Oracle Cloud platform. The first generation Oracle Cloud - now called Cloud Classic - was the result of a somewhat rushed program to gain a foothold in the cloud, largely based on existing software that was not cloud native at all. Many services in this first generation cloud platform were disappointing to users. Functionality was lacking, performance was poor, availability not good enough, pricing not according to a true pay as you go model. With OCI, Oracle rebuild its cloud from the ground up. Benefitting from its own experiences and with many experienced engineers hired from AWS and Azure teams, the Gen2 Cloud overcomes pitfalls, shortcomings and holes that every first generation cloud will suffer from.
OCI has a consistent user experience throughout all services - in the Console, the Command Line Interface, the SDKs (Go, Ruby, Java, Python) and REST APIS. The way automation, security, monitoring, searching and billing is done is intuitive, straightforward and uniform. OCI offers a free tier with a number of always free resources (including compute instances, storage and two database instances), a free 30-day trial and a pay-as-you-go model that for most services starts at really small fees for small consumption.
In this scenario, you will be introduced to a number of generic concepts and cross cutting facilities in Oracle Cloud Infrastructure. You will not yet be using specific services - this is done in later scenarios. You will lay a foundation on which to later build on.