Reference: https://developer.rackspace.com/blog/overview-of-IAM-in-oracle-cloud-infrastructure/
https://docs.oracle.com/en/cloud/paas/content-cloud/administer/create-instance-oracle-cloud- console.html#GUID-4855750C-F400-4FB4-85AA-96CC98FC5A06

Reference: https://docs.oracle.com/en-
us/iaas/Content/Balance/Concepts/balanceoverview.htm#ariaid-title1

Reference: https://docs.oracle.com/en-us/iaas/Content/Network/Tasks/servicegateway.htm#ariaid- title1

Explanation
Oracle Cloud Infrastructure is hosted in regions and availability domains. A region is a localized geographic area, and an availability domain is one or more data centers located within a region. A region is composed of one or more availability domains. Most Oracle Cloud Infrastructure resources are either region-specific, such as a virtual cloud network, or availability domain-specific, such as a compute instance. Traffic between availability domains and between regions is encrypted. Availability domains are isolated from each other, fault tolerant, and very unlikely to failsimultaneously. Because availability domains do not share infrastructure such as power or cooling, or the internal availability domain network, a failure at one availability domain within a region is unlikely to impact the availability of the others withinthe same region.
The availability domains within the same region are connected to each other by a low latency, high bandwidth network, which makes it possible for you to provide high-availability connectivity to the internet and on-premises, and to buildreplicated systems in multiple availability domains for both high-availability and disaster recovery.
Oracle is adding multiple cloud regions around the world to provide local access to cloud resources for our customers. To accomplish this quickly, we'vechosen to launch regions in new geographies with one availability domain.
As regions require expansion, we have the option to add capacity to existing availability domains, to add additional availability domains to an existing region, or to build a new region. The expansion approach in a particular scenario is based on customer requirements as well as considerations of regional demand patterns and resource availability.
For any region with one availability domain, a second availability domain or region in the same country or geo-political area will be made available within a year to enable further options for disaster recovery that support customer requirements for data residency where they exist.

Budgets Overview: A budget can be used to set soft limits on your Oracle Cloud Infrastructure spending.
You can set alerts on your budget to let you know when you might exceed your budget, and you can view all of your budgets and spending from one single place in the Oracle Cloud Infrastructure console.
How Budgets Work: Budgets are set on cost-tracking tags or on compartments (including the root compartment) to track all spending in that cost-tracking tag or for that compartment and its children. All budgets alerts are evaluated every hour in most regions, and every four hours in IAD. To see the last time a budget was evaluated, open the details for a budget. You will see fields that show the current spend, the forecast and the "Spent in period" field which shows you the time period over which the budget was evaluated. When a budget alert fires, the email recipients configured in the budget alert receive an email. Budget Concepts: The following concepts are essential to working with budgets:
BUDGETA monthly threshold you define for your Oracle Cloud Infrastructure spending. Budgets are set on cost-tracking tags or compartments and track all spending in the cost-tracking tag or compartment and any child compartments. Note The budget tracks spending in the specified target compartment, but you need to have permissions to manage budgets in the root compartment of the tenancy to create and use budgets.ALERTYou can define email alerts that get sent out for your budget. You can send a customized email message body with these alerts. Alerts are evaluated every hour in most regions (every four hours in IAD), and can be triggered when your actual or your forecasted spending hits either a percentage of your budget or a specified set amount. Required IAM Policy Reference:
https://docs.cloud.oracle.com/en-us/iaas/Content/Billing/Concepts/budgetsoverview.htm