I’ve heard many times people asking how to convert OST to PST format. Also, people often ask when and why it’s important to perform OST to PST conversion. If you’re not using Outlook with Exchange Server, you have no idea how essential task it can be to convert OST to PST format. Generally, both OST and PST files are very similar to each other. But still, you just can’t open OST in Outlook client without converting it into PST format. By the way, Outlook 2013 and 2016 use OST file as default file format.