A producer's role in film production
A producer takes on many different roles in the making of a film. The brief definition of a producer is someone that manages the production of a film from start to finish. How they acquire the position can happen in various ways. One may be hired by a production company, or they may work independently. In some cases the director is also the producer. Usually the producer oversees the entire business of the film and leaves the creative role to the director. A common schedule for a producer starts with finding the right story or idea, then creating a budget, hiring a director, and lastly distributing the film.
The first step for a producer is to identify the idea for their project. It is helpful to have plenty of relationships with writers. The story or idea can come from books, plays, articles, etc. The goal is to pitch what will sell. After the script is finished or adapted into a screen play the producer will secure the neccessary rights and it will be ready to find funding. 
In most cases production cannot even begin without funding. It is what puts the production into motion. Some producers only hold their title because of their investments in the film. However, a lot of times the producer will have to find the money else where. They will usually pitch the film to investors who will then give them a budget, of course with the hopes of making a good amount back. 
Once a budget has been set it is time to hire a director to turn the thought into a visual reality. A producer may not be in charge of hiring every crew and cast member but they still oversee the entire project. They cannot allow the film to go over budget. Having this responsibility gives the producer the final say on everything. 
Lastly, it is time for the producer to hire a distribution company for the promotion of the film. The Blair Witch project proved it is possible to promote your film without spending a lot of money, but we're not all so lucky. The distribution company will make it available for viewing and have it promoted as well. This is the moment all the hard work the producer has put it shows, hopefully.