My four personal favorite avenues for finding parts are

Mouser.com – Mouser is a popular worldwide component distributor that has a wide range of products. Their selection is (in my experience) not quite as large as Digi-Key’s, but I prefer their website design, the better filtering system, and the more logical component organization.
DigiKey.com – Digi-Key is another popular worldwide component distributor. They probably have the largest component selection of any distributor, have great customer service, and are fast to ship. Overall I would put Mouser and Digi-Key about even, and certainly at the top of the list.
Octopart.com – This is a relatively new service that is like Google for electronics. Octopart searches through many different distributor channels for the part you want. There are many things I like about this service. They always put the datasheet in an easy to find spot, they provide a useful product summary, and show you price comparisons from different distributors. But there are drawbacks, Octopart still seems a bit unrefined and I don’t think it is worthwhile to compare prices from different distributors unless you are only buying a single part or are buying a massive quantity of components and shipping costs are negligible. In a few years Octopart may become the standard for finding your parts, but for now it still has some room to grow.
datasheets360.com – Datasheets360 has a database of over 70 million electronic components, each with a PDF datasheet and is working on scaling the site up to 350 million parts (up to about 180 million in November 2013).  In addition to datasheets they also provide inventory and pricing information from some of the major suppliers. This is a great resource.
This is just my preference, do you have a better method of finding parts? Let me know in the comments below.
Following will be continued in next chapter.
Shirley Xia
Wonderful PCB
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