Normally, a txoko is set up by a group of members who belong to the same group of friends and they go there to prepare meals among themselves or among a member and his guests.
Tradition says that the person who cooks does so freely while the produce is brought by the rest of the group, with the exception, of course, to those basic ingredients which are kept in the txoko's pantry. Once the meal is over,the total cost of the meal is calculated, the appropriate form is filled out, and the document is left with the money in an envelope inside the txoko's box.
Members pay a monthly membership fee which is used to pay for general expenses and each member pays for what he uses (drink or food wise). Members are normally men and until very recently women couldn't go in at all (there are still some which don't allow women, like Gaztelubide in San Sebastian). Nevertheless, the norm is that women usually cannot enter the kitchen.
Main characteristics: A basic feature among all txokos is that the members are the ones that cook and then someone, a member or guest, will do the shopping or bring along the ingredients for the meal. Usually, someone outside the society is hired to deal with the cleaning. As you can imagine, the most important place within a txoko is the kitchen.
Normally, after the meal or in between dishes, the participants sing traditional songs. It is very common in the Basque Country that whole groups of friends of all ages start singing all together, both after a meal or even when they go from bar to bar.
Sociological reasons behind the txokos: Basque people form a matriarchal society. All around the towns as well as in farms or fishing villages are the women who run the home. The man is still considered the head of the family but is the woman who organizes the daily economy and how everything should be done, even in farms where there is an important agricultural and cattle production.
It is said that txokos were created so men could escape from the home and the woman's control, but this is not their purpose anymore. As women gained access to paid jobs outside the home and their qualifications gave them equality in rights, there are very few txokos nowadays which will only accept men.