Summary

Texmaker is a free, modern and cross-platform LaTeX editor for linux, macosx and windows systems that integrates many tools needed to develop documents with LaTeX, in just one application.
Texmaker includes unicode support, spell checking, auto-completion, code folding and a built-in pdf viewer with synctex support and continuous view mode.
Texmaker is easy to use and to configure.
Texmaker is released under the GPL license .

(the structure, the document and the embedded pdf viewer side by side)

(two documents side by side)

Features
Unicode editor

Texmaker is fully unicode and supports a large variety of encodings.
Spell checker

Texmaker includes spell checking while typing.

Code folding

All \part, \chapter, \section,.., \begin{foo} \end{foo} blocks can be collapsed.
Code completion

The main LaTeX commands can be quickly inserted while typing.

Texmaker includes a "structure view" which is automatically updated while typing.
"Master" mode

Texmaker allows you to work easily onto documents separated in several files with the "master mode".
Integrated Pdf viewer

Texmaker includes a built-in pdf viewer with continuous scrolling and synctex support.
Easy compilation

"One-click" compilation with the predefined "Quick build" commands.
Mathematical symbols

370 mathematical symbols can be inserted in just one click.
Wizards

Texmaker includes wizards to generate the most standard LateX code ('Quick document', 'Quick Beamer Presentation' , 'Quick letter', tabular, tabbing and array environments.
LaTeX documentation

An extensive LaTeX documentation is furnished with Texmaker.
Error Handling

Texmaker automatically locates errors and warnings detected in the log file after a compilation and you can reach the corresponding lines in the document in one-click.
Rectangular block selection

Easy rectangular selection with the mouse+Alt key. Users can easily cut/copy/paste columns of a table.
Find in folders

With Texmaker you can search for text in all the latex documents included in a folder (and the subfolders). If you click on a line, Texmaker will open the corresponding document at the right line.
Rotation mode for the pdf viewer
Export to html and odt via TeX4ht
Regular expressions support
Full asymptote support

(syntax higlighting - commands )
Unlimited number of snippets

With Texmaker, users can define an unlimited number of snippets with keyboard triggers