help running provides some hints:
next instuctions (and also
(gdb) help next
Step program, proceeding through subroutine calls.
Usage: next [N]
Unlike "step", if the current source line calls a subroutine,
this command does not enter the subroutine, but instead steps over
the call, in effect treating it as a single source line.
So we can see that
step steps into subroutines, but
next will step over subroutines.
stepi (and the
nexti) are distinguishing by "line" or "instruction" increments.
step -- Step program until it reaches a different source line
stepi -- Step one instruction exactly
(gdb) help finish
Execute until selected stack frame returns.
Upon return, the value returned is printed and put in the value history.
A lot more useful information is at https://sourceware.org/gdb/onlinedocs/gdb/Continuing-and-Stepping.html