A payment gateway is an application that authorises and takes payment for websites. There are two main options when setting up a payment gateway for your site.
Option One Merchant Account With A Bank
This is not to be confused with a bank account. A merchant account is a separate account with a credit clearing bank. These accounts while cheaper on per-transaction fees carry a monthly fee and can be expensive to set up. For more information, there is a great article on merchant accounts here on the UK business forums.
Option Two A Third-Party Payment Processor.
This is the option we recommend for most of our clients. Companies like Paypal, and others will accept payments for you and charge a small commission per payment accepted. For example, Paypal will charge you 3.4% of the sale total plus 30p per transaction. This can go right down to 1.9% and 20p for larger turnovers.
These third-party payment processors are the easiest way to integrate payments with WordPress or most major shopping carts.
There are many different third-party payment processors you need to research to see which ones suit your business best.
As well as companies that take payments instantly you can also ask clients to set up standing orders for recurring fees or send bacs payments for one-off purchases. The challenge with that is it is more work for the customer and can result in an abandoned transaction.
If you take monthly payments from your clients or you offer some kind of service contract where you may want to bill them different amounts for the work you do then you should consider Direct Debit. There is an excellent company called Go Cardless that offer this service. It is free to set up and fees are lower than other payment providers.
Go Cardless is used by HM Government, Trip Advisor, The Guardian and some other very big names so you know this is a trustworthy company.