The MLS Summer Transfer Window officially opened today, meaning teams are now free to add players. The window will remain open until Aug. 9, and applies to incoming transfers as well as trades within the league.
Seattle Sounders fans should be well-versed in all of this by now — few teams have been more active during the so-called “secondary” transfer window — but we wanted to put together a primer of sorts for the uninitiated or those who may have forgotten some of the vagaries.