Short answers, pulled from the story.
DevIL, short for Developer's Image Library, is a cross-platform image library started by Denton Woods. Its goal is to provide a single, consistent API for loading and saving many different image file formats across Windows, Mac OS X, and Unix-like systems.
The library was originally named OpenIL, a name reflecting its OpenGL-inspired design. Silicon Graphics, Inc. requested the name be changed, which led to the library being renamed DevIL.
DevIL supports 43 file formats for reading and 17 for writing. Formats with both read and write support include BMP, DDS, JPEG, PCX, PNG, raw, TGA, and TIFF. The actual available formats depend on which external libraries like libjpeg and libpng were included at compile time.
DevIL consists of IL (the main image library), ILU (the utility library for image manipulation), and ILUT (the utility toolkit that connects DevIL to external graphics APIs like OpenGL, Allegro, Windows GDI, and DirectX). This structure mirrors the corresponding parts of OpenGL.
DevIL is licensed under the LGPL (Lesser General Public License). The Free Software Foundation lists it in its directory of Free Software, and the LGPL allows the library to be used in proprietary and commercial software without requiring the calling code to be open source.
DevIL supports Windows, Mac OS X, and Unix-like systems. Bindings are available for Delphi and Visual Basic in addition to C and C++. The ILUT layer connects the library to OpenGL, Allegro, Windows GDI, and DirectX.