Can't check into TFS Source Control from the Solution Explorer

If you find you can't check into TFS Source Control from the Solution Explorer (i.e. the "Check In..." option does not appear when you right-click on your Solution), you a very likely offline. I put myself offline a moment ago by opening Visual Studio outside of AMD. One may associate anew with Team Foundation Server by going to

File > Source Control > Go Online

(and alternatively one may associate with a different TFS repository by going to

   File > Source Control > Change Source Control...

   which is what I attempted first before being warned of the consequences).

Why commit via Solution Explorer instead of Source Control Explorer? If you commit via the Solution Explorer you are basically just recommitting the contents of your "src" folder (assuming you have a src and lib folder delineation) which is the appropriate scope. I have before committed at the top of everything in the Source Control Explorer and have inappropriately committed a nugget script which broke the build (not that I understand why presently).

i.e. stands for "id est" meaning "that is"