Maestro is a multi-national debit card service owned by MasterCard that was founded in 1992. Maestro cards are obtained from associate banks and can be linked to the card holder's current account, or they can be prepaid cards. The cardholder presents the card at the point of sale (POS) and this is swiped through the terminal by the assistant or the customer or inserted into a chip and PIN device. The payment is authorised by the card issuer to ensure that the cardholder has sufficient funds in their account to make the purchase and the cardholder confirms the payment by either signing the sales receipt or entering their 4 to 6-digit PIN.
Within the EU and certain other countries, Maestro is MasterCard's main debit brand and is the equivalent of signature debit card which does not require electronic authorisation, similar to the Visa Debit card. In most other countries, Maestro is equivalent to a Visa Electron and is MasterCard's tertiary card. It requires electronic authorisation much like a Solo debit card, i.e. not only must the information stored in either the chip or the magnetic stripe be read, this has to be sent from the merchant to the issuing bank, the issuing bank then has to respond with an affirmative authorisation. If the information is not read, the issuer will decline the transaction, regardless of any disposable amount on the connected account. This is different from other debit and credit cards, where the information can be entered manually into the terminal (i.e. by punching the 13 to 19 digits and the expiry date on the terminal) and still be approved by the issuer or stand-in processor.
Maestro is accepted at around twelve million point of sale outlets.
In Germany and Austria, Maestro replaced the Eurocheque system. Austrian Maestro cards are virtually always pure Maestro cards. German Maestro cards, however, are in most cases co-branded with the German Electronic Cash PINPad/Cash Group/Girocard logo. These co-branded cards work like normal Maestro cards within the Maestro network and as Girocards within the Girocard network, but they cannot be used as Maestro over the telephone or on the internet.
In Belgium, Maestro cards are co-branded with the Belgian BC/MC-logo (BanContact Mister Cash).
In the United Kingdom, the former Switch debit card system was re-branded as Maestro. Underneath the branding, however, the system was still the old Switch one and the cards were still fundamentally Switch. In 2011, MasterCard aligned UK Domestic Maestro (the former Switch) with the standard international Maestro proposition, ending its status as a separate card scheme. This change also led to the discontinuation of the Solo (debit card).  In January 2009 First Direct and HSBC discontinued the use of Maestro card, issuing Visa Debit cards to new customers and a gradual roll-out throughout 2009 to existing customers. In September of the same year, the British arms of the National Australia Bank, being the Clydesdale Bank and the Yorkshire Bank, started the process of replacing the Maestro card with a Debit MasterCard for their current accounts, except for the Readycash and Student accounts, for which the Maestro card continues to be issued. Likewise, in the same month the Royal Bank of Scotland Group (Europe's largest debit card issuer which includes the NatWest, Coutts and Ulster Bank brands) switched from Maestro to Visa Debit, a process that took two years to complete. This effectively meant that only a few smaller UK banks would be issuing Maestro cards. However, in 2013 Bank of Ireland (UK) launched a new range of current accounts in Great Britain in partnership with the Post Office, and these come with Maestro debit cards. 
In Ireland, Laser, which was co-branded with Maestro, has been replaced by Visa Debit and Debit MasterCard. The Laser debit card has been phased out by all banks and ceased to operate from March 2014. Irish Laser cards carried Maestro co-branding from 2008 onwards. They were intended to be used with chip and PIN POS systems. The chip on the card was programmed with two applications, one for Laser and one for Maestro. POS transactions were normally processed over the Laser network in Ireland and the Maestro network when the card was used abroad. Some POS terminals prompted users to manually select Laser or Maestro before completing the transaction. Laser cards could be processed as Maestro in most POS terminals worldwide for chip and PIN or swipe and sign transactions (where still accepted). Internet and telephone-based retailers, however, needed to be set up specifically to accept Irish Laser/Maestro cards. Transactions made with these cards were often secured by MasterCard's SecureCode system to verify the cardholder's identity. These cards were usually multi-functional and operated as a debit card as well as an ATM Card which could be used for accessing ATMs. Some banks also allowed customers to use their cards to deposit or withdraw money over the counter or at An Post post offices using their debit card and PIN. Historically the cards often contained a Cheque guarantee card function indicated by a hologram. This scheme was shut down in 2011. Foreign-issued Maestro cards are still accepted in Ireland in ATMs and by many POS machines. However, acceptance of Visa and MasterCard debit/credit cards is more reliably universal at POS terminals.
In the United States, Maestro is a PIN-based debit card network closely related to the CirrusATM network, also owned by MasterCard. Like other PIN-debit networks in the U.S., Maestro there relies solely on a standard card and PIN, without a chip; signature-debit transactions in the U.S. are handled through the main MasterCard network or the rival Visa network. RBS's U.S. subsidiary, Citizens Financial Group, also began a switch to Visa, though like most foreign banks with operations in the United States it uses MasterCard's Cirrus network and the card participates in the MasterCard SecureCode initiative.
In Brazil, Maestro acquired the existing Redeshop service and rebranded it as Maestro. Brazilian Caixa Econômica Federal is currently the major Maestro issuer in the world, with over 34,000,000 cards issued as October 2006.
In Israel, Maestro Cards cannot be used at point of sales locations to make purchases but the Cirrus network is accepted at a majority of cash points most of the time. The exception is the 'First International Bank of Israel' (FIBI) who do not accept Cirrus.
In Sri Lanka, Nations Trust Bank (NTB) issues all its customers with an ATM card, which also doubles as a Debit Card as well it being accepted at other Cirrus ATMs locally and internationally
In China, Bank of China uses Maestro as its "international" debit card system. Also, certain Bank of China ATMs will present the user with Japanese or Korean language options upon insertion of a Maestro card.
In Romania, Maestro is a popular debit card (the third one after Visa Electron and MasterCard Standard Debit), is issued by 7 banks: Unicredit-Tiriac Bank, RIB, BCR, BRD, Raiffeisen, Carpatica and Credit Agricole.
In Russia, Maestro Momentum is the only debit card that is being issued currently. The card is valid only in Russia, and cannot be used for internet payments
In Italy, all banks offer Maestro by default unless a customer asks for a V PAY card, from Visa Inc.
In the Netherlands, almost all banks issue Maestro debit cards, with only one bank offering V PAY instead of Maestro cards. In the Netherlands, banks offer small portable terminals or alternative methods (such as text message) to be used in conjunction with technology called iDEAL, to allow debit cards to be used for online transactions.
In Japan, Maestro debit cards with EMV chips issued outside the Asia Pacific region, the Netherlands and Canada are temporarily unable to be used at ATMs in Japan due to an upgrade to the regional ATM network. In addition, Seven Bank announced in April 2013 that all MasterCard cards, including Maestro, would no longer be accepted at their ATMs due to a disagreement with MasterCard.