Payment gateway is like an encrypted channel that passes the transaction securely from your customer's computer to the financial institutions to capture the authorization and approval. When the transaction is done, information is sent back through the payment gateway to complete the order and provide you with verification. It is also a key for the secure transfer of funds from your customer's credit card to your merchant account. Merchant account is an account obtained from financial institution for processing the credit card transactions. 

So, if you setup a merchant account in a payment gateway company, your web site can accept payment from your customers, via credit / debit card transactions across the Internet in real time. Customers can pay using a number of popular debit and credit cards.

There are many payment gateway companies in the world. You can choose your favourite payment gateway company (based on their charges, services and its brand etc). We can assist you to setup a payment gateway merchant account.

Here are some famous payment gateway company:
www.paydollar.com
www.worldpay.com