Thanks to all for the responses (and for being gentle despite my
ignorance).

My breaker box was labelled when I moved in. However, through trial
and error, it appears to me that the breakers that control the overhead
lights in a room don't control the outlets in that room. For example,
I have a computer plugged in an upstairs room and when I flip the
breaker labelled "3 bedrooms and bathroom" (meaning the upstairs
rooms), the lights stop functioning but the computer stays on. So I
will work through each breaker individually so I can label them more
precisely, and in the process, perhaps I'll reset the appropriate one
for that bedroom's outlets.

I do have a follow-up question: one response mentioned "connections
[that] are backstabbed into holes in the back of the receptacles" and
another response mentioned "a loose connection or fried one in the back
wired push in connections". What is this referring to? The outlets I
have inspected thus far are wired to the screws on either side of the
receptacle.

Thanks again,
Matt