One of the hottest trends today within distributed computing is Web Services. Basically, a Web Service can be described as an XML-based interface that can be used by a client application to invoke a computing service distributed in a network via standard Internet protocols. In order for Web Services to become a ubiquitous technique for program to program communication, however, there need to be a solid framework in place for how Web Services that utilizes the public Internet for transport can be properly protected and secured. As the situation appears today, most services are not publicly exposed but are often deployed inside a corporate, private network. This hampers the vision of Web Services that can be publicly published in directories which potential consumers can search in order to find a suitable service to satisfy their need. This paper describes what the general threats and challenges are in deploying secure Web Services over publicly available and insecure networks, as they are explained in the literature. It then continues to give an overview of some of the more known security standards that are beginning to emerge on the scene.