Infrastructure as a Service (IaaS) is a form of cloud computing that provides virtualized computing resources over the internet. IaaS is one of the three main categories of cloud services, alongside Platform as a Service (PaaS) and Software as a Service (SaaS).

In an IaaS model, a cloud provider hosts the infrastructure components traditionally present in an on-premises data center. These components typically include servers, storage, and networking hardware, as well as the virtualization or hypervisor layer. IaaS providers also offer a range of services to accompany these infrastructure components, such as detailed billing, monitoring, log access, security, load balancing, and clustering, as well as storage resiliency, such as backup, replication, and recovery.

• Elasticity: IaaS allows businesses to scale up and down based on their needs. This means you can increase or decrease resources such as CPU, memory, and storage as required.
• On-Demand Resources: Resources can be provisioned and de-provisioned on demand, providing flexibility and efficiency.

• Pay-as-You-Go: IaaS operates on a pay-as-you-go model, meaning you only pay for the resources you use. This can significantly reduce costs compared to maintaining physical hardware.
• No Capital Expenditure: There is no need for upfront capital expenditure on hardware, which can be a significant financial burden for businesses.

• Remote Access: IaaS resources can be accessed from anywhere with an internet connection, providing flexibility for remote work and global operations.
• API Access: Many IaaS providers offer APIs that allow for automated management of infrastructure, enabling integration with other services and automation tools.

• Redundancy and Backup: IaaS providers often offer redundancy and backup options to ensure high availability and disaster recovery.
• Service Level Agreements (SLAs): Providers typically offer SLAs that guarantee a certain level of uptime and performance.

• Data Protection: IaaS providers implement robust security measures to protect data, including encryption, firewalls, and intrusion detection systems.
• Compliance: Many IaaS providers comply with industry standards and regulations, which can help businesses meet their own compliance requirements.

• Self-Service: Users can manage their own infrastructure through a web-based interface or API, providing control and flexibility.
• Monitoring and Analytics: IaaS platforms often include tools for monitoring resource usage and performance, as well as analytics to help optimize infrastructure.

Let's consider a practical example of using IaaS to set up a virtual machine (VM).

1. Sign Up for AWS: Create an account on Amazon Web Services (AWS).
2. Navigate to EC2: Go to the EC2 (Elastic Compute Cloud) dashboard.
3. Launch Instance: Click on "Launch Instance" to start the process of creating a new VM.
4. Choose an Amazon Machine Image (AMI): Select an AMI, which is a template that contains the software configuration (operating system, application server, and applications).
5. Choose an Instance Type: Select the type of instance based on the required CPU, memory, and storage.
6. Configure Instance Details: Set the number of instances, network settings, and other configurations.
7. Add Storage: Specify the storage requirements for the instance.
8. Add Tags: Optionally, add tags to help manage and organize instances.
9. Configure Security Group: Set up firewall rules to control traffic to the instance.
10. Review and Launch: Review the configuration and launch the instance. You will need to create or select a key pair for SSH access.

In this section, we have defined Infrastructure as a Service (IaaS) and explored its key characteristics, including scalability, cost-effectiveness, accessibility, reliability, security, and management. We also provided a practical example of setting up a virtual machine on AWS, demonstrating how IaaS can be used to quickly and efficiently provision computing resources. Understanding these concepts is crucial for leveraging IaaS effectively in various business scenarios.