What Component Is This?
Start with what the thing looks like rather than counting legs, because parts come with one, two, three, four, eight or forty of them. Every path ends with a name and what to do next.
What sort of thing is it?
Cylinder with a wire each end. What is on the body?
Legs out the bottom. What is the body?
How many legs, and what shape?
What is printed on it?
Not sure? Both live in the same package. The number decides, so search it plus the word datasheet.
A block with pins. Which one?
Surface mount. Which shape?
Mechanical parts. Which is it?
When the wizard shrugs
Anything with a part number printed on it surrenders faster to a search for that number plus the word datasheet. The first page has a picture, the pin names and what the thing is for, which beats guessing by shape every time. This tool exists for parts too small, too old or too worn to read.
Three measurements that settle most arguments
Diode mode separates a diode from a resistor in one poke: a diode reads about 0.6 V one way and open the other, a resistor reads the same both ways. Continuity mode maps which legs of a switch, button or relay are joined. And resistance mode tells a coil (a few ohms) from a resistor (whatever it says on the body) when the markings have worn off.
Counting legs is not enough
Leg count narrows things down but never finishes the job: two legs covers resistors, capacitors, diodes, LEDs, crystals, fuses and inductors; three covers transistors, regulators, resonators and trimmers; four covers optocouplers, bridge rectifiers and buttons. Shape, markings and one measurement get you the rest of the way.