Projects are always done for a purpose. You do projects to get something done... to change something.
Let's say, you want to get your house repainted - well that's your project - your project changes your house from having old paint to new paint.
Considering "repainting of your house" as the project, let's talk about some of the key people (roles) involved in the project.
Stakeholder: Since, we talked about changing something, it means that there is someone who actually wants that change. In case of repainting your house, that person is either you or your husband/wife/partner. Let's say that your wife's been nagging you to get the house repainted; she's choose all the colours and has everything dreamt up. So, she becomes what we call a stakeholder (in this case a key stakeholder). Stakeholders are the people who are effected by the project in some way or another. If you and your kids live in the house, you too become stakeholders (probably not "key" stakeholders as the wife has the most stake in the project).
Sponsor: Now, everything in this world costs money. So, you need money to have the house repainted. If you have the money in your bank account, you can use that money. In this case you become what is called a "Sponsor". Sponsor is the person who provides money for the project. If at any point in time, more money is needed than originally planned, you'd be the person who'd be nagged.
Project Team: You know how to paint your house, but unfortunately, you don't have enough time this summer. So, you decide that you'd hire a painting shop to get the job done. You go find a place in the town-centre and after checking them out, you decide to hand them over the project. You talk to the Store Manager (Mini) and she provides you the quote. After a bit of negotiations between the two of you, you finally agree on the price and she does the booking for next to next Thursday through Sunday. She confirms that there will be two contractors (Tom and Jerry) who'd do the actual work. She'll be visiting once a day to check progress and make sure it's delivered on schedule and on budget.
So, Mini and Tom and Jerry comprise of what is called your "Project Team". Project Team is the group of people responsible to get the project done.
The exact composition of a Project Team (the lingo) could vary from project to project. Developers are always included in a project team (in case of software projects). Testers are generally included as well. Project Managers are also generally included. Stakeholders are generally not included. However, you may still find scenarios where they are included.
Project Manager: Mini is more precisely, what is called a "Project Manager". Project Manager is the person who's responsible to make sure the project is completed and delivered on time, on budget and at the required level of quality.
Tester/Quality Assurance: Once you're back home, you believe that you've chosen the right people to do the job, but it might be better if you could do a check of the work before you pay for it. Now, you'll be working on your computer a bit that day and you're not sure how much attention you'd be able to provide to inspecting the work. So, you ask your daughter (Dora), who's got a keen eye for details to do an inspection before you have to pay for the work. She becomes what we call a "Tester" or "Quality Assurance" person. "Tester" or "Quality Assurance" person is the person who's responsible to ensure that work is done up to the desired level of quality.
Below is a simple example of a software development project's different players. There can be multiple stakeholders, developers and testers. A good number of times you'll also find multiple business analysts. Projects managers multiply only in case of very complex projects or programs. Sponsors multiply if one single sponsor does not have enough money. However, its a rare scenario. And if there are more than one sponsor, your project will most certainly tend to get more complicated.
Well, there are many more roles involved in a complex project. But for today we'll wrap it up at this. Hope it was helpful in understanding the basics of a Project, Project Management and the roles involved in Project Management.