Terms aligned with Dr. Sherif Mostafa's CS432 lectures.
| Term | Definition |
|---|---|
| Cloud computing | Ubiquitous access to shared pools of configurable resources, rapidly provisioned with minimal management, often over the Internet; pay-per-use utility model. |
| Elastic computing | Ability to dynamically and on-demand acquire computing resources for variable workloads. |
| Multiplexing | Sharing resources among apps whose peak demands are not synchronized → higher utilization. |
| CAPEX | Capital expenditure — upfront hardware/software purchase. |
| OPEX | Operational expenditure — pay-per-use, no large start-up costs. |
| IaC | Infrastructure as Code — manage/provision IT infrastructure using code, not manual config. |
| Virtualization | Creating a virtual (software-based) version of a physical resource (servers, storage, network). |
| Hypervisor | Software layer between hardware and VMs that allocates resources to each VM. |
| Host machine / Host OS | Physical device and its OS on which virtualization runs. |
| Guest OS / VM | Virtual machine and its OS, isolated from other VMs. |
| Type 1 hypervisor | Bare-metal — installed directly on hardware (ESXi, Hyper-V, KVM). |
| Type 2 hypervisor | Hosted — runs as app on host OS (Workstation, VirtualBox). |
| KVM | Kernel-based Virtual Machine — Linux kernel module; each VM is a regular Linux process. |
| SELinux | Security-Enhanced Linux — enforces security boundaries around KVM VMs. |
| Live migration | Moving a running VM between physical hosts without service interruption. |
| IaaS | Infrastructure as a Service — rent VMs, storage, network (EC2). |
| PaaS | Platform as a Service — build/deploy apps without managing OS (App Engine). |
| SaaS | Software as a Service — provider-delivered apps (Gmail, Salesforce). |
| FaaS | Functions as a Service — serverless event-driven functions. |
| Grid computing | Early model — aggregate resources from multiple locations for scientific computing. |
| Utility computing | Early model — provider charges for specific usage, not flat rate. |
| Community cloud | Infra shared by organizations with common concerns. |
| Multi-cloud | Using multiple public cloud providers simultaneously. |