LinkedIn has rapidly become one of recruiters’ most valued tools for identifying fresh talent. In particular, human resource professionals are flocking to the site because of its legions of “passive job seekers” — those who aren’t looking for a new position but might be convinced to jump ship for the right opportunity.

However, even though LinkedIn may be one of today’s fastest-growing ways of finding new workers, it’s worth noting that more established recruiting tactics and tools still account for a larger share of new hires.

Here’s a look at the three most common sources of new hires in today’s labor market.

(For more on LinkedIn’s rise, check out this story from Capital Business.)

Job boards: Many people in the recruiting industry have been quick to pronounce that online job boards such as Monster and CareerBuilder are on their way to extinction. So it may be surprising to learn that sites of this kind were the source of 18.1 percent of external hires in 2012, according to an annual survey by human resources consulting firm CareerXroads. That means these sites were the third most common method for hiring new employees last year. Job boards also still command a sizeable portion of recruiters’ spending. A 2011 assessment by talent consulting firm Bersin by Deloitte found that recruiters spend about 14 percent of their budgets on these sites.

But if many talent professionals deride these tools as passe, why are they still used so frequently? The answer, experts and recruiters say, is that the job boards remain a fairly effective way of finding individuals for jobs that are relatively low-skill and high-volume, such as those in the retail or hospitality industry.

But for professional positions, use of these sites seems to be declining at many organizations. For example, Teresa Green, managing director at Arlington-based corporate research firm CEB, said the company has shifted some of its recruiting dollars away from these sites.

“I noticed the traditional job boards were yielding less hiring for us, and potentially less quality,” Green said.

Career sites: Employers continue to see a steady flow of candidates apply to positions via their own corporate career Web sites. These job seekers accounted for 23 percent of hires in 2012, according to CareerXroads. However, the proliferation of smartphones and tablets have presented a challenge to this model. Many employers have not adapted their job Web sites for use on the devices, meaning the application process is extraordinarily cumbersome for mobile users.

“Companies are figuring out other ways to get people to apply using fewer keystrokes,” said Gerry Crispin of CareerXroads, including using autofill and multiple-choice options.

Referrals: For all the innovation that has occurred in the business of talent sourcing, recruiters say referrals are perhaps the most tried-and-true method that yields the best results. Referrals accounted for 24.5 percent of external hires last year, more than any other source.

The old-fashioned recruiting technique hardly exists in a vacuum: Referrals often are happening via contemporary channels. For example, one could use LinkedIn, Facebook or some other platform to introduce a hiring manager and a prospective worker.

But no matter how the contact is initiated, many employers say referrals remain their best source for attracting new workers that are a good fit for their organization.