Exposing Apex Methods As SOAP Web Services
You can expose your Apex classes and methods so that external applications can access your code and your application through the REST architecture.
Apex SOAP Web services allow an external application to invoke Apex methods through SOAP Web services.
Apex class methods can be exposed as custom SOAP Web service calls. This allows an external application to invoke an Apex Web service to perform an action in Salesforce. Use the webService keyword to define these methods.
For Example: To create an account and insert it in Salesforce.
global class MyWebService
webService static void makeAccount()
// Your code here