Financial & Legal
You can find a definition and further details on CDI/CDD contracts here:
Hope that helps!
CDIs are like gold dust, as they give you a lot of rights under French law. Most French companies will try and avoid giving you a CDI at all costs, although they aren't supposed to. They do things like change the job description of the CDD slightly, so it counts as a different job. Not surprising given how hard and expensive it is to make people redundant here (if you wondered why lots of people don't do any work, it's probably because they are essentially unsackable). The benefit of the CDD is that you get the 10% bonus at the end, and you can leave more easily!
People with a CDD seem to pay less taxes than those with a CDI. At least I pay a lower tax rate than my CDI counterparts. CDDs require less notice when leaving (only 2 weeks compared to 3 months) and allow employers to hire people as needed. One of the issues with a CDI if you are a small business, is that it is hard to hire and fire people that you need if they are all "permanent employees" or CDI, which are hard to get rid of. So many don't hire the staff that they need when they need it, which doesn't help keep people employed. A CDD contract is suppose to elevate this problem.