After completing and verifying a good capture, you should save the bulk (all captured packets) capture file (assuming a single file capture) to your directory of choice. You will later be filtering and saving a subset of packets to a smaller file, but it is advantageous to be able to load the original capture file again at a later time if during the analysis you discover that you might have inadvertently filtered out more packets than you wanted.

Using the Save As option in the File menu, navigate to the directory of your choice and give the file a name. If no file extension is specified, Wireshark will append a file extension based on the Save as type option selected; the default is the .pcapng format. However, you can save the file in several other popular vendor-specific formats if you intend to share the capture file with someone who is using a different protocol analysis tool.

If multiple files were saved using one of the multiple file and/or ring buffer capture...