Directory provide a back link for a web site?

Directory submission is useful but do not use this method blindly. First find some high page rank reputed directories and then submit articles on these.

Directory submission is a good link building technique for build quality baklinks and increase the traffic of your website. It is use for save your links in internet using directory submission websites like you save mobile number of your known person in phone directory. If directory moderator approve your website links, your links stable for long time and it is good for ranking of your website. It is a cost effective way to build quality backlinks. There are thousand quality websites, which allow you to post your links on their website.

If the directory is Do fallow yes then you get one.

Yes directory submission is an important way to promote a website.directory submission increases the traffic and it is a good source of quality backlinks.

Backlinks, also known as incoming links, inbound links, inlinks, and inward links, are incoming links to a website or web page. In basic link terminology, a backlink is any link received by a web node (web page, directory, website, or top level domain) from another web node.
Inbound links were originally important (prior to the emergence of search engines) as a primary means of web navigation; today, their significance lies in search engine optimization (SEO). The number of backlinks is one indication of the popularity or importance of that website or page (for example, this is used by Google to determine the of a webpage). Outside of SEO, the backlinks of a webpage may be of significant personal, cultural or semantic interest: they indicate who is paying attention to that page.

It is true that Directory Submission was too good for SEO but after Panda update, Directory Submission is not more beneficial compare then before panda update.