GDB
acronymprogrammingsecurity
Stands for: GNU Debugger
The GNU debugger: it runs a program under control so you can stop it, inspect it, and step through it.
The core moves are a breakpoint to pause at a chosen line, backtrace to see the call stack that got you there, print to read variables, and step or next to advance. It is the tool that turns a crash into an explanation, since a segfault plus a backtrace usually names the offending line immediately. Security researchers and reverse engineers use the same tool from the other direction, watching memory as a program mishandles it.
Also known as: gdb, debugger, breakpoint