UDDI:  UDDI stands for Universal Description, Discovery and Integration and built in to Microsoft .NET platform. It works as a directory which is used to publish and discover public web services. It communicates via SOAP (SOAP is a simple XML-based protocol that allows applications to exchange information over HTTP).
WSDL: WSDL stands for Web Service Description Language and is a W3C specification which defines XML grammar for describing Web Services. Means it is written in XML and also specifies the location of the service and the operations (or methods) the service exposes.XML grammar describes details such as:-
1.    Where we can find the Web Service (its URI)?
2.    What are the methods and properties that service supports?
3.    Data type support.
4.     Supported protocols

DISCO: DISCO is the abbreviated form of Discovery; it is the file that helps .NET discovers local 
services. Basically it is used to club or group common services together on a server and provides
links to the schema documents of the services it describes may require.  It contains WSDL (Web
Service Description Language) when one searches for the Web Services; it will go to the DISCO
which gives actual information about the particular