Cielo is the largest Brazilian credit and debit card operator. Cielo is the biggest payment system company in Latin America by revenue and market value.
Brazilian Company of Means of Payment, dba VisaNet, was founded in 1995 as a joint-venture between Visa International and the banks Bradesco, Banco do Brasil, Banco Real (currently Banco Santander), and the now defunct Banco Nacional.
Its purpose was to create a common infrastructure to be used by all banks issuing Visa cards, instead of each bank having a separate technological solution to process credit card transactions.
On July 1, 2010 VisaNet was renamed Cielo and was no longer the only processor of Visa cards in Brasil, following a regulation by the Brazilian government.
Its main competitor, Rede, was now allowed to process Visa cards, and Cielo was allowed to process Mastercard, Diners Club and other cards which were only processed by Redecard.
According to en.wikipedia