If somebody starts an open source project (for example with a GPL license) where people will make contributions, than who will own these contributions in the level of the whole project? Will the new code become the property of the original author or the contributors will be authors too?Who has the right over the ongoing project? For example who has the power to release the code in a second license? The original author only? Can the contributors separately do that as well, or do they have to make a joint decision with the original author and all of the contributors?
Who has right over the code that comes from contributions in an open source project?
licensing;open source
Each author retains copyright to their code.  If the project is under the GPL, contributing the code requires that the code is licensed under the GPL.  If you want to do something else with the code like releasing it in a different license, you'd need the permission of the original author.For many projects, the project owner requires contributors to assign copyright to contributed code to the project owner.  This makes it possible to, for example, release GPL projects under new versions of the GPL license as those are released since it quickly becomes impractical to chase down hundreds of individual contributors in these cases.