My "toolkit", when it comes to computers, is a handful of software applications I just can't live without. They are some of the first applications I install on a new computer, and I carry them everywhere on a thumb-drive so if I have to work on a strange computer, I'm not without my favorite utilities.
Irfanview is one of these cherished applications. There are a lot of free image-viewing utilities available these days (Google's own Picassa is probably the best known), and modern operating systems offer built-in image preview. So why the oddly named Irfanview?
Although not designed as an image editor, the software can be used to tweak pictures; it has the usual bevy of options to crop, re-size, sharpen color balance and otherwise adjust the image. Unless you are heavy into graphic design, Irfanview will almost certainly meet your needs for image handling.
There are a few areas where Irfanview is weak. The first is minor: its default icons, used when you associate images to the program, are atrocious. They look embarrassingly amateur and are a bad first impression for the program. However, the lack of support for any cloud-based image stores (Picassa Web Albums, Flickr, Photobucket or a host of others) may be a serious disadvantage for some users. Personally, I'm not willing to stick all my personal images onto the insecure cloud and prefer to keep them on local storage so I'm fine with this "missing" feature but I can understand if others consider this a problem. It is one of the reasons IrfanView loads so quickly, though. Finally, it lacks any real integration with the operating system.
But its speed and tiny footprint more than make up for any perceived disadvantages. It's free software and frequently updated with new features. I expect to be using Irfanview for years to come.