Hi Mercedes Patalano

There are two reasons. (1) The publishers have to meet some expenses to publish the journals. So, they ask the authors to pay. (2) Some publishers do this like a business and they collect money from the authors. I would like to suggest that there are a number of OA journals which are not charging publication fee. You may get the list from DOAJ (www.doaj.org)

Hi Rathinasabapathy:

Thanks for your reply. What it happens.It is that publishers have moved the cost of publishing a magazine for the readers or users to the authors, and I think they should think about other sources of funding, if they want to edit a magazine in open access.

  Otherwise using the mode magazine subscription fees.

Greetings Mercedes