# Introduction

## Chapter 1. Introduction

Regina is a software package for 3-manifold topologists. Its main strengths lie in normal surface theory, angle structures, and the combinatorial structures of 3-manifold triangulations. Beyond this, Regina can perform a range of other algebraic, geometric, topological and combinatorial tasks; see the full feature set later in this introduction.

## Getting Started

Not sure how to start Regina? You can find it in your main applications or programs menu; follow this link for details and screenshots.

The best way to become familiar with Regina is simply to play around with it. Regina ships with several example files, including a number of censuses of 3-manifold triangulations. Most of these examples can be accessed through the File->Open Example menu when running Regina.

For an excellent starting point, try File->Open Example->Introductory Examples, which illustrates most of the structures that Regina can work with. The users' handbook (which you are reading now) also includes a number of sample Python sessions that illustrate how Regina's in-built Python scripting can be used.

The graphical user interface offers extensive assistance through tooltips and "What's This?" texts. If you ever want to know what element of the user interface means (such a button or a text field), just press Shift+F1 and click on the thing you would like to know more about.

As a final note, users are encouraged to write to `<regina-user@lists.sourceforge.net>` with any questions or comments. See the user services page for further details.