I was looking at a schematic in a recently published advanced-hobbyist article, and there it was, again: the venerable 2N2222 transistor, this time in a role as a relay driver. It's not a high-performance device, especially by today's standards, but it has good mid-range specifications. Introduced in the early 1960s, it was one of the first silicon transistors commercially introduced, and helped bring germanium's role as the leading semiconductor material to an end. It is a well-behaved, well-understood, reasonably rugged, very inexpensive small-signal component.
Even today, decades after it was introduced, it is available from at least a dozen vendors in almost countless packages. The 2N2222 was introduced in metal-can TO-18 case, then a metal-can TO-5, and in 1965, a lower-cost plastic T0-92 package. [BTW, you can read a fascinating, first-person recollection about its development by its lead engineer, at "A Transistor Museum Interview with Jack Haenichen".]
Most components in our industry have short lives. ICs for consumer products, of course, have the shortest, while power semiconductors, industrial components, and RF parts tend to have longer ones. It's nice to know that there are parts which are still readily available, and still viable for new designs, even after the equivalent of "forever" in our high-tech world. Even better for designers, it's now available in many packages, numerous versions, fully characterized, has no performance surprises, and with an almost uncountable number of application notes and design tips.
Are there any active or passive components in the RF-design world that have comparable longevity and viability? Let me know if any come to mind, I can be reached at email@example.com.♦