Hardware Against Software Piracy (HASP) is a technology that allows us to provide a physical (USB) CD Key (used with the HASP module) instead of the traditional 6 digit Ignition CD Key. This allows users to quickly move a license from one computer to another.

Human Machine Interface (HMI) is the user interface that allows people to interact with PLCs in their facility. Ignition's Vision module allows you to use it as an HMI by launching a client. Systems that monitor and control entire plants and provide historical and statistical data are often referred to as HMIs.

 HyperText Markup Language (HTML) is the authoring language used to create documents on the World Wide Web. HTML defines the structure and layout of a Web document by using a variety of tags and attributes. The correct structure for an HTML document starts with <HTML><HEAD>(enter here what document is about)<BODY> and ends with </BODY></HTML>. All the information you'd like to include in your Web page fits in between the <BODY> and </BODY> tags. - webopedia

HyperText Transfer Protocol (HTTP) is the protocol for moving information across the Internet. All webpage addresses begin with "http://" or "https://" (for a secure connection) but most new browsers hide this from you. We say Ignition uses HTTP to communicate between the Clients and the Gateway. This just means that Ignition is using an existing, proven technology to transfer its information throughout the network.

Generally a reference to OPC-HDA. 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