Originally and still most commonly a
mail-order music club, though they have also branched out into
videos and
DVDs and
CD-ROMs.
Columbia House licenses music with the major labels so they can produce their own copies of albums legally. Then they sell these by mail order and through their web site.
Because they generally only sell what they are licensed to copy, you won't find some albums there that you can find in your local record store. On the other hand, they may carry some albums that small record stores have decided aren't worth the space on their shelves. Also, most new albums from popular artists are only available in the music clubs several months after they go on sale in stores. This is the only way Columbia House can offer the deals it does; the big money from CDs comes in the first few months after the release of an album by an already-popular group.
They entice people to join the club with offers of lots of free CDs, but read the fine print. You have to buy a certain number of regularly-priced CDs ($15 to $18 plus shipping) to complete your membership agreement. You also have to pay something like $2.50 per CD shipping and handling per CD (somewhat less in your big initial membership shipment), so they aren't really free but they're still cheap -- it makes the regular-price albums that much more expensive, though.
They have lots of different offers, but most common is 12 to 14 free CDs, with a membership requirement of 5 or 6 regular-price CDs, and an offer to buy one CD at a discount but counting as one of the ones for your membership requirement, and get an additional one or two free.
How to make the most out of Columbia House
If you join, always take the offer of the discounted CD and extra free CD or two. It is better than anything they will offer you after you join.
After you join, make sure you always refuse their monthly selections (except in the extremely unlikely case that a monthly selection is something you want and don't already have) and watch for their buy-one-get-one-free and buy-one-get-two-free offers. Use these to complete your membership requirement. Make lists of albums you want to buy that are offered by the club. Search their web site; you can order anything they have available at any time, except that some albums are not available in initial memberships (and marked as such on the web site); ignore the listings in the mailings they send you. If there are any double albums you want that are offered in the club, check whether they count as two selections toward your agreement. Some do, and these are generally cheaper than any other two albums you would want to buy; also, the shipping charge is less than two individual albums. Use these to complete your agreement; you can generally get other double albums free in the buy-one-get-N-free when you buy a double album, though, as always, you pay for the higher-priced album. And once you complete your agreement, quit the club. They will soon beg you to rejoin, at which time you can get a whole new batch of "free" CDs.
Overall, you can get your cost per CD down to $4-$5, counting double albums as 2, if you follow these guidelines. Of course, this is limited to the music that is available in the club. BMG Music Club has a slightly different list of albums available, and different membership rules (you don't have to buy so much after you join, but they offer a lot fewer "free" CDs too; it works out to the same but you don't have to buy as many at once).
Use the clubs to fill out the holes in your CD library that you missed for some reason or another.
Of course, a lot of people these days seem to be just using Napster instead, but this is legal while that's not, and this gets you the actual CD, all insert material in the case (older albums sometimes lack inserts), etc.