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IT glossary
Plain-language definitions for the acronyms and terms you'll hear from IT, HR, and software vendors. Skim once, search by browser find (Ctrl+F / Cmd+F) when you need it.
Accounts & Access
Sign-in and identity
SSO (Single Sign-On)
One sign-in (usually your work email and password) that unlocks several apps. If you sign into Microsoft or Okta and then click into another app without being asked again, that's SSO.
MFA (Multi-Factor Authentication)
The second step after your password — a phone prompt, a six-digit code, a security key. Stops most account takeovers even if your password leaks.
Tenant
Your firm's "instance" of a cloud service like Microsoft 365 or Adobe. When IT says "wrong tenant," they mean you signed in with an account from another organization.
Conditional Access
Rules that decide whether you can sign in: from this device, from this country, with MFA, etc. If sign-in fails for no obvious reason, conditional access is often why.
Devices & Management
Your computer and phone
MDM (Mobile Device Management)
Software that lets IT manage settings, push apps, and (sometimes) wipe a device. Intune (Microsoft) and Jamf (Apple) are the common ones.
BYOD (Bring Your Own Device)
Using your personal phone or laptop for work. See BYOD basics for what this usually means in practice.
Endpoint
IT-speak for any device that connects to the network — laptop, desktop, phone, tablet. "Endpoint protection" is antivirus and security software running on those devices.
Image / Imaging
The standard configuration of a new computer at your firm — the apps, settings, and policies pre-installed before you receive it.
Network
Connections and infrastructure
VPN (Virtual Private Network)
A secure tunnel that makes your laptop appear to be on the office network even when you're at home. Required for some internal apps and shared drives.
Cloud PC / Virtual Desktop / Citrix / AVD / Windows 365
A Windows desktop that runs on a server in a data center. You see it through a window on your real computer. Useful for accessing internal apps without VPN.
DNS (Domain Name System)
The phone book of the internet. Translates "outlook.office.com" into a numeric address. When DNS breaks, websites stop loading even though your internet is "up."
Firewall / Proxy
Network gear that filters traffic in and out of the company. Often the reason a vendor app "can't reach the activation server."
Files & Collaboration
Where things are stored
OneDrive vs. SharePoint
OneDrive is your personal cloud folder for work files. SharePoint is the team / department version. Both are Microsoft and both sync to your computer through the OneDrive app.
Box, Dropbox Business, Google Drive
Other cloud-file services. Same idea as OneDrive / SharePoint but a different vendor. Some firms use one of these instead of (or alongside) Microsoft.
Mapped drive (Z:\, P:\, F:\)
A letter on your computer that points to a folder on a server somewhere on the company network. Often requires VPN if you're remote.
Permissions / ACLs
Who can read or write a file or folder. "I don't have permissions" usually means a folder owner needs to add you, not that anything is broken.
Email & Meetings
Outlook, Teams, Zoom terms
Distribution list (DL) vs. Microsoft 365 group vs. Teams team
DL = old-style email-only group. M365 group = email + shared mailbox + shared files. Teams team = M365 group + chat + channels. They overlap but aren't the same.
Shared mailbox
A second mailbox (like info@firm.com) that several people can read and reply from. You add it in Outlook, you don't sign in as it.
Calendar delegate
Someone you allow to read or edit your calendar on your behalf. Common for executives' assistants.
Out-of-office (OOO) / Automatic replies
The away message Outlook or Teams sends while you're out. Set both internal and external versions if your firm exposes it.
Security
Threats and protections
Phishing
Email or text trying to trick you into giving up a password or clicking a malicious link. See recognizing phishing.
Ransomware
Malware that encrypts your files and demands payment to unlock them. The reason backups exist.
Zero-day
A security flaw that vendors and defenders learn about at the same time as attackers — no patch available yet.
EDR (Endpoint Detection & Response)
The grown-up version of antivirus. Watches for suspicious behavior on each computer and alerts security if something starts acting like malware.
Vendors
Common product brand names
Microsoft 365 / Office 365
Word, Excel, PowerPoint, Outlook, Teams, OneDrive — sold as a subscription. "M365" and "O365" are the same thing; M365 is the newer name.
Adobe Creative Cloud
Photoshop, Illustrator, InDesign, Acrobat — subscription bundle. Different from Adobe Acrobat Sign (e-signatures) and Adobe Acrobat Pro (PDF editor).
Autodesk / Bentley / Trimble
The big three engineering / construction software vendors. AutoCAD, Revit, Civil 3D = Autodesk. MicroStation, OpenRoads = Bentley. SketchUp, Trimble Connect = Trimble.
Esri ArcGIS
Mapping and GIS software. ArcGIS Pro is the desktop app; ArcGIS Online is the web/cloud version.
Tickets & Support
Words you'll see in IT replies
Ticket / case
A tracked record of your IT request. Reference it by number when following up.
Escalation
Moving a ticket to a higher tier of support — usually because the first responder couldn't resolve it.
SLA (Service Level Agreement)
The target time IT commits to respond to or resolve your request. "P1 / Sev 1" tickets have the shortest SLAs.
RCA (Root Cause Analysis)
The post-incident write-up explaining what actually broke and how it'll be prevented next time.