Craigslist is the brainchild of Craig Newmark, and has become one of the most popular sites on the Internet. Started in San Francisco in 1995, craigslist is perhaps the ultimate site for classified listings. It offers job advertisements, personal ads, ads for cars, pets, home supplies and a plethora of other choices. The website is built around communities, and craigslist now offers sites in 450 cities and countries throughout the world. Financial information about the nonprofit company is not disclosed, but business experts believe craigslist is worth over 10 million US dollars (USD).

For the most part, posting and reading ads on craigslist is free. The revenue made from craigslist is generated by people posting job ads at significantly below market rate. As of 2004, job ads for large businesses cost 75 USD in San Francisco and the surrounding Bay Area. In other cities and countries, job ad postings cost 25 USD. To post an ad in the "gigs" section of the want ads is free. Craigslist does not post banners ads, preferring to earn money only through job posting revenue.

The lowered rate for posting want ads has made craigslist a proverbial thorn in the side of more traditional companies offering classified ads. Newspapers, in particular, have attacked craigslist on numerous occasions for posting advertisements that might be construed as endorsement of illegal activities. Craigslist sections that sell puppies, for example, were part of a lawsuit suggesting craigslist illegally endorses puppy mills or the sale of outlawed breeds. The San Francisco Chronicle sued craigslist for this purpose, but the suit was dismissed.

It is true that craigslist does seriously undercut competitive newspapers through its classified ads. This is especially the case for ads other than jobs. A person wanting to sell a sofa, a car, or rent property, saves a lot of money by listing on craigslist instead of in a newspaper. In fact, they pay no money for doing so, whereas they would pay quite a bit to a large city newspaper.

Those who use craigslist, which reports over 5 billion page views per month, have learned to be cautious about advertisements posted there. While most job ads are legitimate, personal ads, housing rentals, and for sales ads can be phonies, meant to gather people’s personal information or lure them into danger. Jobs in the gigs section are often “work for free” opportunities, or scams advertising great jobs if one will take a course or pay a fee for job listings. It’s reasonable to use craigslist with a great deal of caution, and certain areas of craigslist sites are reserved for adults only. People using restricted areas must register with craigslist, and inappropriate postings can be flagged by other viewers.

Lack of moderation on craigslist postings are perhaps the primary reason why this Internet giant is criticized. There are currently only 10 craigslist employees, and moderating the more than 500,000 job ads posted each month would be a very significant undertaking. This would not even include moderating all the free ads and postings generated by users. Many users take it upon themselves to flag postings, or to write comments on other posts that seem to abuse the free exchange offered by craigslist.

Some caution should be observed when using craigslist because no moderation exists on the site. You should be wary about giving out personal information like telephone numbers or addresses. If you answer a personal ad and arrange a meeting, do so in a public place. If you plan to respond to a “for sale” ad, go with several people to pick up or view the items for sale. If a job ad asks for a resume, do not include personal information until you verify the company’s existence. Avoid “too good to be true” ads, because they usually are.

With caution, craigslist can be an excellent site for searching jobs or for finding just about anything. Also, craigslist has numerous forums for people seeking information about new cities they may be visiting or moving to. Some users of craigslist devote time to “watchdog” blogs so that other users can check out the claims of craigslist ads prior to responding to them.