Glossary: Delphi

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Delphi projects are full of component and library names nobody outside that world recognises. Below are the terms that turn up in a quotation or a handover file, with what each one is and what it means for maintenance and upgrades.

Updated on 28 August 2026

The language and the environment

VCL
The library of windows, buttons and grids almost every Delphi desktop application is built with. Windows-specific, which partly determines how easily an application can move to the browser.
Unicode
Since Delphi 2009 a string is Unicode by default. That is the hardest threshold when upgrading from an older version: everywhere characters were treated as bytes has to be reviewed.
Lazarus and Free Pascal
A free development environment and compiler that sit close to Delphi. Sometimes the better route, for instance when an application also has to run on Linux.
Package and component
Reusable building blocks installed into the environment as a library. In an upgrade each one needs a version that comes along.

What you meet in a project

TMS WebCore
An extension that runs existing Delphi code in the browser. The route to a web version without rebuilding everything.
DevExpress
A widely used set of interface components: grids, charts, editors. Actively maintained, so there is usually a version matching your target Delphi.
FireDAC
Delphi’s current database layer and generally the destination when the BDE or ADO is replaced.
QuickReport and FastReport
Reporting components. QuickReport is the classic stumbling block in an upgrade; FastReport is the usual alternative.

Not sure which components sit in your application? That can usually be derived from the project file. It is the first thing we map as a matter of course.

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