ACL
Access Control List
A list of rules that says which network traffic is allowed or blocked.
Why it matters in everyday business: Like a security guard checking a list at a door.
PLAIN-ENGLISH REFERENCE
Technical Glossary for Business IT
Networking, servers, storage, fibre and security terms explained without assuming the reader already works in IT.
This glossary explains what a term means and why somebody running or supporting a company would care about it. Product-specific limits and standards requirements still belong in the relevant technical chapter.
Active Directory
Active Directory
Microsoft's central directory for users, computers, groups and access control in a Windows domain.
Why it matters in everyday business: One staff account can be managed centrally instead of separately on every PC.
AD DS
Active Directory Domain Services
The Windows Server role that provides the Active Directory directory and domain authentication.
Why it matters in everyday business: It gives the company one managed identity system for people and computers.
Apache
Apache HTTP Server
A widely used web server that serves websites and web applications.
Why it matters in everyday business: One Linux server can host internal or public business websites.
Backup
Backup
An independent recoverable copy of data or system state.
Why it matters in everyday business: It is the safety net for deletion, corruption, ransomware, hardware loss or major mistakes.
Certificate
Digital Certificate
A signed digital identity that binds a name or system to a public key.
Why it matters in everyday business: Browsers, VPNs and servers use certificates to prove who they are and encrypt connections.
Container
Container
An isolated application environment that shares the host operating-system kernel rather than emulating a full computer.
Why it matters in everyday business: Applications can be packaged consistently without needing a full VM for each one.
DHCP
Dynamic Host Configuration Protocol
A service that automatically gives devices IP settings such as address, gateway and DNS.
Why it matters in everyday business: New laptops and phones can join the network without manual IP configuration.
DNS
Domain Name System
The service that translates names into IP addresses and helps Windows domain clients find services.
Why it matters in everyday business: People and applications can use names instead of remembering network numbers.
Docker
Docker
A platform for building and running containers from images.
Why it matters in everyday business: It helps deploy the same application package consistently on development, test and production systems.
ESXi
VMware ESXi
VMware's bare-metal hypervisor for running virtual machines on physical servers.
Why it matters in everyday business: It is the virtualization layer used in many existing enterprise VMware environments.
FSMO
Flexible Single Master Operations
Five special Active Directory roles for operations that should not be handled independently by every domain controller.
Why it matters in everyday business: They prevent certain directory operations from conflicting with each other.
GPO
Group Policy Object
A set of centrally managed Windows settings that can be applied to users or computers.
Why it matters in everyday business: IT can enforce security and configuration settings across many PCs at once.
HBA
Host Bus Adapter
A controller that connects a server to storage, commonly SAS or Fibre Channel.
Why it matters in everyday business: It is the server's interface to certain storage devices or storage networks.
Hypervisor
Hypervisor
Software that lets one physical server run multiple isolated virtual machines.
Why it matters in everyday business: One powerful server can safely run several separate business servers.
Image
Container Image
A read-only package containing an application and its required files used to create containers.
Why it matters in everyday business: IT can deploy the same known application build repeatedly.
IOPS
Input/Output Operations Per Second
A count of how many storage read/write operations complete each second.
Why it matters in everyday business: It helps describe workloads with many small file or database operations.
iSCSI
Internet Small Computer Systems Interface
A protocol that carries block-storage commands over IP networks.
Why it matters in everyday business: A server can use remote storage almost as if it were a local disk.
KVM
Kernel-based Virtual Machine
Linux kernel virtualization technology that turns Linux into a hypervisor.
Why it matters in everyday business: A Linux server can run Windows and Linux virtual machines.
LACP
Link Aggregation Control Protocol
A protocol that combines compatible Ethernet links into one logical bundle.
Why it matters in everyday business: It can add capacity and keep a connection alive if one member link fails.
Latency
Latency
The delay before an operation or packet completes.
Why it matters in everyday business: Users experience high latency as slowness even when headline bandwidth looks good.
libvirt
libvirt
A management layer and API for virtual machines and hypervisors such as KVM/QEMU.
Why it matters in everyday business: Tools can manage VMs consistently instead of controlling each process manually.
MPO
Multi-fibre Push-On
A multi-fibre optical connector used in high-density and parallel-optics systems.
Why it matters in everyday business: Many fibre strands can be connected in one compact interface.
NAS
Network Attached Storage
A storage system that serves files over the network, commonly with SMB or NFS.
Why it matters in everyday business: Teams can share company files from one centrally managed device.
NAT
Network Address Translation
A router or firewall function that changes IP addressing as traffic crosses a boundary.
Why it matters in everyday business: Many private office devices can share one public Internet address.
Nginx
Nginx
A web server and reverse proxy commonly used for websites, APIs and application front ends.
Why it matters in everyday business: It can serve websites or route incoming web traffic to application servers.
NTFS
NTFS
A Windows filesystem that supports detailed permissions and other filesystem features.
Why it matters in everyday business: It controls who can read, change or delete files on Windows storage.
NTP
Network Time Protocol
A protocol used to keep system clocks aligned.
Why it matters in everyday business: Correct timestamps let logs from switches, servers and firewalls be compared during an incident.
OLTS
Optical Loss Test Set
A fibre test method for measuring end-to-end insertion loss.
Why it matters in everyday business: It proves how much optical power the installed fibre path loses.
OSPF
Open Shortest Path First
A dynamic routing protocol that lets routers exchange topology information and calculate paths.
Why it matters in everyday business: If a routed path changes, routers can learn another path automatically.
OTDR
Optical Time Domain Reflectometer
A fibre tester that sends pulses and measures reflections/backscatter to locate events along a link.
Why it matters in everyday business: It can show where a splice, connector, bend or break is located.
PAT
Port Address Translation
A form of NAT that lets many internal connections share one public address by tracking transport ports.
Why it matters in everyday business: Hundreds of users can browse the Internet through one public IPv4 address.
PKI
Public Key Infrastructure
The systems, policies and certificates used to prove identity and build encrypted trust.
Why it matters in everyday business: It lets company systems trust certificates instead of accepting any device that claims to be legitimate.
PoE
Power over Ethernet
Technology that sends DC power and Ethernet data over the same twisted-pair cable.
Why it matters in everyday business: A camera or access point can be installed with one network cable instead of a separate power outlet.
Proxmox
Proxmox VE
A virtualization platform built around KVM virtual machines, LXC containers and web-based management.
Why it matters in everyday business: It packages many Linux virtualization tasks into one management platform.
QEMU
QEMU
Software that provides virtual hardware and runs guest VM processes, commonly used with KVM.
Why it matters in everyday business: It supplies the virtual devices a guest operating system expects.
RAID
Redundant Array of Independent Disks
A method of combining drives for capacity, performance and/or tolerance of certain drive failures.
Why it matters in everyday business: A failed disk does not always mean immediate data loss, but RAID is not a backup.
Replication
Replication
The process of copying data or VM state to another system or location.
Why it matters in everyday business: It can shorten recovery time after a server or site failure, but copied corruption can also replicate.
RPO
Recovery Point Objective
How much recent data the business can afford to lose.
Why it matters in everyday business: It determines how often backups or replication need to run.
RSSI
Received Signal Strength Indicator
A measure of received wireless signal strength.
Why it matters in everyday business: It helps show whether a WiFi client can hear an access point strongly enough.
RTO
Recovery Time Objective
How long the business can tolerate a service being unavailable.
Why it matters in everyday business: It helps decide how much redundancy and recovery automation are justified.
Samba
Samba
Open-source software that implements SMB services on Linux and Unix-like systems.
Why it matters in everyday business: A Linux server can provide Windows-compatible shared folders.
SAN
Storage Area Network
A dedicated storage network that presents block storage to servers.
Why it matters in everyday business: Multiple servers can use centrally managed storage without treating it like a normal file share.
SMB
Server Message Block
The main Windows file-sharing protocol.
Why it matters in everyday business: It commonly lets staff open shared folders such as Finance or Projects.
Snapshot
Snapshot
A point-in-time storage or VM state used for short-term rollback depending on the platform.
Why it matters in everyday business: It can quickly undo a bad change, but it is not automatically an independent backup.
SNMP
Simple Network Management Protocol
A protocol used to read device status and counters and receive management events where supported.
Why it matters in everyday business: Monitoring can warn IT about failing links or high utilisation before users call.
SNR
Signal-to-Noise Ratio
The difference between useful wireless signal and background noise.
Why it matters in everyday business: Good signal can still perform poorly if interference or noise is also high.
STP
Spanning Tree Protocol
A Layer 2 protocol that prevents Ethernet loops by blocking redundant paths until needed.
Why it matters in everyday business: It stops a cabling loop from flooding the whole switch network.
Syslog
Syslog
A standard way for network and server devices to send event messages to a central log system.
Why it matters in everyday business: It gives IT a timeline of what happened during an outage.
Throughput
Throughput
The amount of useful data moved in a period of time.
Why it matters in everyday business: It helps describe how fast large backups, files or storage transfers can complete.
Trunk
VLAN Trunk
A link that carries traffic for multiple VLANs using tags.
Why it matters in everyday business: One cable between switches can transport several separated networks.
vCenter
VMware vCenter
VMware's central management system for multiple ESXi hosts.
Why it matters in everyday business: Administrators can manage hosts, clusters and VMs from one control point.
vCPU
Virtual CPU
A virtual processor assigned to a VM and scheduled onto the host's physical CPU resources.
Why it matters in everyday business: It is how a VM gets computing time without owning a physical processor.
Virtual Host
Web Virtual Host
A web-server configuration that lets one server host multiple websites using different names or addresses.
Why it matters in everyday business: One server can host several business websites separately.
Virtual Machine
Virtual Machine
A software-defined computer with virtual CPU, memory, disks and network adapters.
Why it matters in everyday business: A company can run a domain controller, file server and Linux application as separate servers on one host.
VLAN
Virtual LAN
A logical Layer 2 network that separates devices even when they use the same physical switches.
Why it matters in everyday business: Staff, cameras and guest WiFi can be kept apart without buying a separate switch for each.
VM
Virtual Machine
A software-defined computer running on a hypervisor.
Why it matters in everyday business: It behaves like a separate server even though it shares physical hardware.
Volume
Container Volume
Persistent storage kept separately from the short-lived container filesystem.
Why it matters in everyday business: Company data can survive when an application container is replaced.
vSwitch
Virtual Switch
A software switch inside a hypervisor that connects VM network adapters to each other and to physical networks.
Why it matters in everyday business: It is the virtual equivalent of plugging server cables into a network switch.