Free Advise about Job and Employment:

An employment website is a web site dealing specifically with employment or careers. Many employment websites are designed to allow employers to post job requirements for a position to be filled. Some employment sites describe differenct job descriptions or employers. Through a job website a prospective employee can locate and fill out a job application or submit resumes over the Internet for the advertised position.

Employment pre-Internet
Before the Internet enabled Employment Websites to advertise job positions, employment opportunities were limited to browsing the classifieds section of the paper, word of mouth and TV. Job seekers were required to find current work related classified ads in their area which imposed geographical limitations upon the individuals wanting to find employment outside of their State or Country.
Once a job was located the job seeker would have to type a cover letter, print out their resume and either personally deliver, send by mail, or overnight express their application to the employer. This task was not hard to do but was very expensive, time consuming and limited the number and area of employment an applicant could apply.

Employment post-Internet
While many Job Seekers still use classic methods to find jobs, Employment websites provide Job Positions in real time all over the world.
What used to take weeks now takes minutes. Employment websites now allow the applicant to find a job opening then submit an application/resume through password protected software and webmail.

Employment websites have completely changed the way employers look for qualified job applications. Today, Job Seekers can search, browse and apply any time they wish regardless of time or day of the week.

Single attribute lists
Some sites allow users to select single attributes, or qualifications, from a list, such as "software" or "database" and then allow users to search on those qualifications individually or combinations of these qualifications. This is an excellent way of providing a filtered search based on certain qualifications.

Multiple attribute lists and qualification trees
A few employment websites, allow users to select multiple attributes, or "qualifications", sometimes arranged in hierarchical format. If an employment website takes the approach of allowing employers to post jobs with specific qualifications, and candidates to post their candidate information with specific qualifications, they can run into the problem of having a very large number of qualifications to deal with. Arranging the qualifications in a hierarchical or tree format can make the qualification trees much easier to use and search on.
All of these are different implementions of allowing employers and candidates to post jobs using discrete qualifications. A discussion of various methods if implementing job websites using discrete qualifications follows:

Different ways of designing job websites using searchable attributes (or qualifications)

Text search and attribute list methods
Text Search - Certainly "text search" is the easiest qualification search method to use and implement. This consists of a user typing qualifications in a text window, and the employment site searching for matching words in its database. This is just like doing a text search on an internet search engine such as Google or Yahoo. The method after this allows job site users to select their qualifications from a list of unique qualifications.
Attribute List - Some job sites allow users to select unique qualifications from a qualification list. This seems to be useful in helping with searches, but this approach has its limits. The list of unique qualifications is usually too short and is not comprehensive enough, or it quickly becomes very long, and there is no way to define relationships between qualifications. This makes it difficult for users to find the qualifications they're looking for, and also leads us to the flexible hierarchy or qualification tree concept.

Flexible hierarchy methods
Flexible hierarchies can be further subdivided into a generic flexible hierarchy and a partially subdivided flexible hierarchy.
Generic Flexible Hierarchy - This method of organizing qualifications has the virtue of making it easier for users to find their unique qualifications and, if the site is well organized, makes it easier for users to search and find the exact candidate or position they're looking for. This is a very good method of arranging unique qualifications, as long as an extremely well thought out structure is put into place. However, if an extremely well thought out structure is required, why not try a partially subdivided flexible hierarchy?
Partially Subdivided Flexible Hierarchy - This is the same as the flexible hierarchy except that a structure is placed at the top of the hierarchy to make it easier to guide users down a path that will lead them to the qualification they're looking for. This is designated as a "partially" subdivided hierarchy since not all paths of the qualification tree are subdivided, only those that aid in the navigation of the tree. This is the best of the solutions where unique qualifications are defined. It does take some getting used to, but with practice it can exceed the usefulness of the text-based search method.

Strict hierarchy and matrix methods
Strict Hierarchy - More complex than the flexible hierarchy, the strict hierarchy makes qualifications completely unique - qualifications only appear once in the qualification tree (in the example above, the qualification "database" could only appear in one branch of the qualification tree).
Matrix - Finally, the matrix form of qualification organization is certainly the most complex. In the matrix form, all qualifications exist in a huge n-dimensional matrix, and the matrix designer must choose the intersection points between qualifications to define qualification relationships for the matrix. How someone could design this and present it to users on a web page, in a simple and usable fashion, is beyond me. We are kept busy enough in regular 4-dimensional space. However, who knows what the future holds?