I have been involved in a lot of talk about film Development and have recently set up several Development Companies to help fund feature films as well as a TV Series. Before you can make a movie you have to develop it- like any new endeavor it needs organization and a plan. A movie is actually a business venture and should be set up like you are starting a company.
A Development company isn't a movie. It is the entity that will organize to make the movie. If it's a studio its already set up. If you are a Production company you may also be in a position to develop movie projects. If you are a Producer the best way to set your movie making wheels in motion is to set up and fund a Development Company.
What you can do in your Development Company is pay to option a book or script, engage professionals to help you re-write the script or get materials together to pitch investors. If you really want to be prepared to approach money sources you will also need the best creative marketing materials and a Line Produced budget. Development can include many normal business expenses.
Whatever you spend on your pitch reel and pitch materials is "Development". For a TV series, don't spend a lot because you'll never get it back. The money you do spend on shooting a reel is part of the deal.
Wahoo a free trip to Cannes! Not exactly. Travel to the Cannes Film Market is a legitimate expense of a movie if you actually make a DEAL while you are there, not 'talk to people'. Everyday business and professional services are acceptable expenses. Development is not a free ride but it is money you can get paid back to you through your movie budget. (By the way; your Investors and friends at the IRS won't buy the Cannes trip.)
All the money you put into getting ready to make your movie, television show or web series is "Development", keep track of it.