On almost every day of the year the career Web site Monster.com has more than 40,000 résumés posted in its database.

Figuring out where the résumés go, how they get there, and what makes the difference between getting picked up by an employer and being left in some cyber black hole can be a daunting task.

But the days of snail mailing an application in response to a job opening are gone, and, according to those who design the systems recruiters and employers use to track applicants, the more you know about how to use the new technology the better prepared you will be to land the job you want.

“When you look at the technology that’s in place now you really have to make it easy for recruiters to pick out your résumé,” Eric Winegardner, director of product adoption at Monster.com, said. “The technology is so mainstream that you are really at the mercy of the recruiters who log on to these databases to find candidates.”

When recruiters go searching for candidates on databases such as Monster’s they usually use a word search technology to find résumés that match the terms they are using to describe their ideal applicants, Winegardner said. Knowing what they are looking for often means the difference between being part of the list retrieved by these searches and being left out in the cold.

“If a recruiter was trying to find an accountant with Sarbanes-Oxley experience [the new accounting laws passed in 2002], they might enter Sarbanes-Oxley but they will also enter SOX into their key word search,” Winegardner said. “What you want to do is find out what the relevant terminology that describes your experience in your industry is and make sure you include it on your résumé.”

Job searchers should also make sure they are checking in at least once a month to keep their résumés up to date and remind the Monster system that they are still looking. Most employers only search for applicants who have visited their online résumé within the last month. The idea, Winegardner explained, is to keep your résumé living and breathing, to make sure you are part of the searches recruiters are doing.

The rules that apply for Monster.com are mostly the same for other online applicant-tracking systems, whether those run internally by companies or other career Web sites.

“There are hundreds of companies serving this software niche, and to tell the truth they are not all that different,” said David Manaster, CEO of ERE Media, a newsletter for the human-resources industry. “Though there are lots of technical things that differentiate the software, it’s not rocket science.”

As the technology to sift through applications and track candidates develops, Manaster said, companies are trying harder to develop software that doesn’t make a mistake and miss the best talent.

“The best people with the qualifications most in demand are getting harder and harder to find,” he said. “And frankly most of the software out there isn’t that great in parsing out the data. If I’m the kind of hot shot a company really is looking for, how much time do I have to put together the perfect résumé? What employers want to make sure they are not doing is missing these people.”

Manaster also mentioned how important it is for applicants to use industry-appropriate key words for the jobs they want. He suggested getting in touch with people who have similar positions to the ones they are trying to get and asking them how they describe their jobs. He also stressed paying close attention to the words and phrases employers use when advertising a position.

“The best indications of what an employer is looking for are the words and phrases they use to describe the job,” Manster said. “With hundreds of thousands of candidates, they are very particular in showing what they want and indicating how to respond.”

The largest applicant-tracking software producer in the United States, Kenexa, said it is trying to screen questions to help employers narrow down the initial number of résumés they search.

With a market share of about 25 percent, Kenexa works with large employers such as General Electric, Yale University and Liberty Mutual. These companies have thousands of applicants for almost every position they advertise, Becky Sterling, global practice leader of Kenexa’s talent management division, explained. Narrowing down the number of applicants at the beginning can be a big help.

“We try to go beyond the word search and help employers spend the most time with qualified candidates,” Sterling said. “You have ability as a client to say we have so many candidates for these jobs that the first thing we want to do is pre-qualify these résumés for a particular skill or particular background.”

Even with these more advanced systems, Sterling stressed, the most important thing candidates can do to help their résumés move along is to make sure they are thorough.

“Two bullet points are not enough anymore,” she said. “You have to continually go back and make sure you are selling yourself appropriately.”