In a way, it could be described as a tool to be a bit more lazy!
Every japanese person is receiving one, if not several, throughout their live. I'm not a japanese person, but I received one on my very first day there, when arriving at my guestparents home! "Here, this is for you, use it!"
The stamps are made from different materials, beginning with plastic and ending with expensive ones like special and expensive types of woods or stone. Despite to the technological advancing, they are still used a lot, and there are 4 different "types" of Hankos.:
Jitsuin (実印): These ones are used for "special occasions", like bying cars, bying a house, bying land, marrying, and similar higly official events. They are registered seals, usually they are rectangular and carry the full name of the person holding it. They are kept in a secure place, and used rarely throughout ones life. Foreign people with an alien-registration card can register them too.
Ginkō-in (銀行印): These are also hidden carefully, because they are used for banking. Imagine your credit card being stolen, this would make a similar problem! They are also custom made to prevent copy thieves. And the banks surely have a registration for the stamps that are used at their place...
Mitome-in (認印): These are used to sign for mail deliveries, signing letters, and so on. Those are the ones that are practically and used day by day, so of course, they also don't need to be hidden! Most of the time it has the family name only. I imagine this can cause quite some confusion, as many people share the same family names, but it seems to work out.... And there are also versions for private documents only, like private letters. Most of the time they are round or oval shaped. For the most common names, premade ones can be bought, usually made of plastic. Usually the ones for males are larger, and might be square, too.
Gagō-in (雅号印): For the artistic type of persons, to sign their works of art. And as usually for artists, they can come with any size, with nicknames, with slogans and phrases, just what the artist wishes for!
For a matter of fact, mine is made out of wood, and I think it's custom made, my name is not common there for sure.
It's my name, writting in Kanji (the way my guestparents chose the writing, I guess). And since I'm interested in the meaning of names....:
Ri:里 Village/ native place
Amu:編 Editing/ (part of a) Book/ completed poem
The way my guestparents translated it was like: "Restoring an old village to make it more beautiful." What a name, huh? :P
Well, and google translations' version of putting the Kanji together is...."Published by Misato", ahahaha. Just who is Misato now?
And what I just discovered right now....appearantly there are starting to be such stamps with yourself as an anime figurine!