OST or Offline Storage Files represent the user's mailbox data in offline mode on the local machine upon registration with Exchange Server using Microsoft Outlook. It is automatically created on the first use of Microsoft Outlook upon connectivity with the server. Once the file is created, the data is synchronized with the email server so that it is available offline as well in case of disconnectivity from the email server.
SVG files are Scalable Vector Graphics Files that use XML based text format for describing the appearance of image. The word Scalable refers to the fact that the SVG can be scaled to different sizes without losing any quality. Text based description of such files make them independent of resolution. It is one of the mostly used format for building website and print graphics in order to achieve scalability.
You can also convert OST into many other file formats. Please see the complete list below.