Irfanview

Irfanview is a program used to look at porn while you're at work. It is like ACDSee except it's not utterly retarded and can browse images in a folder by pressing space and backspace or by using the mouse-wheel if you can afford anything other than a serial mouse (although it is unlikely you can because you are looking at porn and not with a woman and thus have no money). You can exit Irfanview by fumbling over yourself to hit the escape key when your boss shows up behind you, which is where he is right now. Irfanview does nothing other than supporting image formats and windows now supports all so no need to download this shit. People used this instead of entering serial numbers for acdsee. FACT.

Other Uses

Image Compression

Use this shit to compress the fuck out of your images, especially before uploading them to ED. Most compressed images don't lose quality so, y'know, be cool and download it.

Color Correction

It can also be used by camwhores as a means of spreading internet disease, as shown below with gamma/contrast/saturation correction.

Batch Rename and Conversion

Pressing "b" shows a window can be used to batch rename and convert images for people with OCD.

Icons

Unlike many other programs, Irfanview can save in .ico format, meaning you can have different icons than everyone else for the same programs, which I assume is more convenient or efficient somehow.