Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Most plastic and metal ICs and transistors have the identification printed on them, you just have to look up the data sheet. Some very small transistors (like sot-23) don't have room for more than 2 symbols, so identifying them is difficult. There is a cross-reference website, but I have lost the URL.
The little hobby function is why we wise technicians and hobbyists NEVER throw away a data book. I have IC, diode and transistor databooks on my shelf from the early 1970s. We don't throw those away just because the devices are no longer manufactured or because the manufacturer has published a newer edition of the book -- we keep them because some of that obsolete data is no longer available anywhere else, including on the Internet. For instance, I have several editions of the Motorola Optoelectronics databook and Motorola has sold that line to other companies. I still have the books because I have a lot of those Motorola parts in my stock, I might find some of those devices in circuits that I'm repairing or I might find a "surplus" dealer that has some of those devices.