hello cosplay!

What is cosplay?

Cosplay (コスプレ, kosupure?), short for "costume play", is a type of performance art in which participants don costumes and accessories to represent a specific character or idea. Characters are often drawn from popular fiction in Japan, but recent trends have included American cartoons and Sci-Fi. Favorite sources include manga, anime, tokusatsu, comic books, graphic novels, video games, hentai and fantasy movies. Any entity from the real or virtual world that lends itself to dramatic interpretation may be taken up as a subject. Inanimate objects are given anthropomorphic forms and it is not unusual to see genders switched, with women playing male roles and vice versa.

The appearance of cosplayers at manga events makes such events a popular draw for photographers. As this became apparent in the late 1980s a new variant of cosplay developed in which cosplayers attended events mainly for the purpose of modeling their characters for still photography rather than engaging in continuous role play. Rules of etiquette were developed to minimize awkward situations involving boundaries. Cosplayers pose for photographers in designated areas removed from the exhibit hall. Photographers do not press them for personal contact information or private sessions, follow them out of the area or take photos of exhibits in the hall itself without permission. The rules allow the symbiotic relationship between photographers and cosplayers to continue with the least inconvenience to each.

A lot of time has passed but during those decade, the hobby was spread outside the japan boundaries thanks to the success of the japanese comic and anime culture.
Infact, there are strong cosplay communities in most of Europe and America. Italy in particolar, being exposed to anime and manga (japanese Comics) since the middle of the 80s has produced an impressive number of Cosplayers and almost every comic fair has his fair cut of people strolling around in costumes.

Being a cosplayer is a state of mind: there's more than simply create or buy the costume. Usually people know deeply the characters that they are going to portray: it's almost necessary because you have to win the approval of the other cosplayers. Almost always people ask you to take some picture and you're required to copy the "signature positions" of the character you are playing.
It's not required to act, unless you decide to create a gag for the audience, but you should at least mimic some of the expressions and poses of the character.