Merchant services is a broad term to describe various services that help businesses do business. These include a wide range of financial services and can include software and hardware products. Merchant payment processing is by far the most important merchant service for retailers.
Merchant service providers (MSPs) are companies that provide the services that enable merchants to process many kinds of payment methods. For brick-and-mortar merchants, this includes credit/debit card payments, contactless payments, and mobile wallet apps. Online stores use merchant service providers to process their online sales.
MSPs provide other services in addition to payment processing. This includes
POS hardware like credit card readers. Software solutions include virtual terminals, payment gateways, and online shopping carts.
Merchant service providers go by many names- acquirers, merchant account providers, payment services providers, and payment gateway providers. Basically, any company that allows you to accept non-cash payments is an MSP. They make their money by charging businesses for the services they provide.
Which the merchant service provider is right for your business depends on a lot of factors. You need a provider that offers all the services you need, but at a price point, you can afford. However, before you can get started, you're going to have to open a merchant account.