White hat is doing Search Engine Optimisation in a clean acceptable (to the search engines) way.
Black hat is using techniques which the search engines would frown on, for example cloaking and serving one page to the search engines and another to human visitors.
tangor
7:52 am on Jun 16, 2010 (gmt 0)
seo1589, welcome to webmasterworld!
White hat is no tricks, just solid HTML, CSS, JS, SQL Black hat is serving tricks, traps, dealing from bottom of the deck, taking lessons from politicians and lawyers. Usually means exactly what Mark_A said above: serving one page to search engines and something completely different to users, usually by sniffing out IP ranges or User Agents. What "wealth" one can make black hat is very limited, once the SE's figure it out, site is banned. White hat, on the other hand, gets a fairly decent chance at making long term wealth.
idolw
9:24 am on Jun 16, 2010 (gmt 0)
Black hat is simply manipulating the search engine results pages using a number of methods including: - hidden text and hidden links; - cloaking - described above as showing one page version to engines and another version to real users; - taking part in link schemes, especially automated; - using doorway pages, i.e. pages built only to set up a cookie on user's computer
In general... anything that looks dodgy at first sight.
httpwebwitch
2:33 pm on Jun 17, 2010 (gmt 0)
etymological note: the idiom references idealized western movies where the hero always wears a white hat and the villain wears black. Whether this is factual is not the point.
Actually I suspect it's not so much the western movies, but the Looney Tunes parodies of those westerns with Daffy Duck that solidified the white/black hat uniform. That's my theory.
Mark_A
3:13 pm on Jun 17, 2010 (gmt 0)
Indeed, at one point there was a frowning on 1x1px transparent gifs because people were keyword stuffing the alt text and getting a result from it.
I thought it was a great shame as I used 1x1 transparent gifs a lot as spacers and shims and the like. Mind you I never associated any alt text with them! :-)
rocknbil
6:05 pm on Jun 17, 2010 (gmt 0)
Well . . the appropriate alt text is
alt="spacer image"
or something like it, which nullifies the possibility of penalties for "spacer abuse." That technique is not dead, BTW, saw it on a client site just yesterday in a bit of tracking code from an SEO company. Sometimes you just have to nod and keep quiet . . .
jedz
7:47 am on Jul 7, 2010 (gmt 0)
Black hat is simply manipulating the search engine results pages using a number of methods including: - hidden text and hidden links; - cloaking - described above as showing one page version to engines and another version to real users; - taking part in link schemes.
onepointone
8:52 am on Jul 7, 2010 (gmt 0)
Never done blackhat, but from the little research I've done, it extends well beyond manipulating SE's. If you violate anyones TOS or promote ripoffs...
Things like: Stuffing affiliate cookies, automated spamming of forums, forms, or blogs, making people sign up to email lists in order to get a 'gift' they never get, etc. Some blackhat could be illegal. Its not just confined to a nuisance for search engines.