Web directories are catalogs of internet resources, specializing in categorizing and classifying sites, divided into categories and subcategories intended to cover all or part of visitors' interests. Web directories are one of the most effective link building resources. To reach the top positions in Google, a website needs as many links to it.
These links may be obtained from the web directory submission. The web directory submission is get links from quality, being practical life obtained by a simple registration. Most links obtained from a web directory submission are dofollow (page rank transfer), which is also very important. Also directory submission is a good way to find business partners through registration, the site will be listed in a certain category of web directory with description and contact information.
Web Directory submission must be done manually. If you use automatic or semi-automatic programs you risk that the site is not inscribed correctly that the site is not approved / posted in web directories. Carefully selected web directories that make registration, web directory submission not recommend you require reciprocal link or posting icons, banners .. etc. because it is not effective and may even affect page rank site scored.
There are many hypotheses regarding unauthorized term "ideal" to do a web directory submission, but the fact is that no official information or exact such a process. Basically if you enroll in one day site in 200 folders validation and display web site or indexing link sent directly to site scorer can take between two days and 4-5 weeks, so link by site-s are obtained in the course of a month.
In conclusion properly register manually, Google will not penalize your site. Beware of web directories resembling farms or links that might be penalized by Google.