Why Black & White? - Because b/w pictures are always attracting. Colour might sometimes be bright / dark or it can be warm / cold, but Black & White pictures are simple lights and shadows, nothing else. That’s the major reason why it’s a favourite way to express certain situations.
In Digital Photography, Black & White pictures did not disappear. With a bit of feeling for the light and colour, you are able to easily re-produce black & white pictures that can even be more interesting than older ones.
As this is only an introducing article about the different black & white conversions, this is not where you can find the detailed articles about converting! - You can find them in the Photoshop Tutorials section of Post-Processing!
Many cameras allow direct conversion to black & white. My personal advise is to not use that feature, because you have much more options in Adobe Photoshop© (if you have it). This will give you the freedom to choose when you want a picture to be black & white, and when not.
You can also make multiple versions (both colour and b/w) of that image, then.
As you will notice, there are many ways to convert a picture to Black & White. But a sophisticated conversion to black & white is more than a simply change in the mode to greyscale.
In the following links you will find special articles about conversion for different images. Some are best used for portraits, others for landscape photography, etc..
You can then choose which way you prefer and use it for your own pictures and conversions.
For general information on this topic, you can listen to TFTTF show 17 - Converting to B&W.