It is designed to be simple for beginners and powerful for professionals.
IrfanView seeks to create unique, new and interesting features, unlike some other graphic viewers, whose whole "creativity" is based on feature cloning, stealing of ideas and whole dialogs from ACDSee and/or IrfanView!
(for example: XnView has been stealing/cloning features and whole dialogs from IrfanView, for 10+ years).
IrfanView was the first Windows graphic viewer worldwide with Multiple (animated) GIF support.
One of the first graphic viewers worldwide with Multipage TIF support.
The first graphic viewer worldwide with Multiple ICO support.
Some IrfanView features:
32 and 64 bit version
Many supported file formats
Multi language support
Paint option - to draw lines, circles, arrows, straighten image etc.
Toolbar skins option
Lossless JPG rotation, crop and EXIF date change (also in batch mode)
Slideshow (save slideshow as EXE/SCR or burn it to CD)
Show EXIF/IPTC/Comment text in Slideshow/Fullscreen etc.
Support for Adobe Photoshop Filters
Fast directory view (moving through directory)
Batch conversion (with advanced image processing of all files)
Multipage TIF editing
Multiple undo steps
Support for embedded color profiles in JPG/TIF files
Change color depth
Scan (batch scan) support
Add overlay text/image (watermark)
Effects (Sharpen, Blur, Adobe 8BF, Filter Factory, Filters Unlimited, etc.)
Extract icons from EXE/DLL/ICLs
Shell Extension PlugIn
Option to change menu hotkeys (right mouse click on menu)
Many command line options
Only one EXE-File, no DLLs, no Shareware messages like "I Agree" or "Evaluation expired"
No registry changes without user action/permission!
and much much more