Overall Equipment Effectiveness quantifies how well a manufacturing unit performs relative to its designed capacity, during the periods when it is scheduled to run. OEE is a measure of Availability, Performance, and Quality.

Original Equipment Manufacturer. A company that manufactures a product (typically a hardware product) that is then duplicated with little or no changes as it is sold to many customers. IE: a company that makes printing presses is an OEM and sells to facilities that use the printing presses.

Open Process Connectivity (OPC) is the name of a technology standard used to write to PLCs. OPC allows information exchange between gauges, databases, programmable logic controllers (PLCs), and more.

An OPC Server is a software application that acts as an API (Application Programming Interface) or protocol converter. An OPC Server can connect to a device such as a PLC, DCS, and RTU or a data source such as a database or HMI to translate the data into a standard OPC format.

OPC Unified Architecture (OPC-UA) is a communication protocol for interoperability developed by the OPC Foundation. The Foundation's goal for this project was to provide a path forward from the original OPC communications model (namely COM/DCOM) to a cross-platform service-oriented architecture (SOA) for process control, while enhancing security and providing an information model.

 Using the OPC-UA module, Ignition acts as an OPC-UA server, serving data collected by its built in drivers to other Ignition modules, as well as third-party OPC-UA clients. -Wikipedia

Often referred to as just 'Tags', OPC Tags are Ignition tags that specify an OPC server and address which drives their values. The OPC address will be subscribed at the rate of the tag's scan class during configuration, and values written to these tags will be pushed to the PLCs.

The underlying software that runs on a computer and provides the user an interface to that computer. Common examples are: Microsoft Windows MacOS X Linux

A relational database. Ignition connects easily to it and can use it to store or retrieve data.

Historical Data Access is a specification for exchanging archived, or historical, process data. A contrast to OPC-DA, which only deals with real-time data. OPC Foundation's HDA specifications