I got a question where someone asked me how to "play movies on Apple computer". The answer to this depends on what you mean by playing movies.
The reason I'm mentioning this is because the person who asked just said they wanted to know "how to play movies on Apple computer" and did not mention if they meant a DVD movie, a movie that they downloaded off the Internet, or a video file (or movie) on a web page. Depending on which they mean, the answer is a little different.
First off, let's assume that when they said "play movies on Apple computer" that they meant a DVD movie.
Well, that's a very simple answer: any Mac (Apple computers are called Macs, with specific models like iMac, MacBook, etc.) made in the last several years can play DVDs. 99% of the time, just pop the DVD in the drive, and DVD Player will open automatically and start playing the movie.
Worst case scenario, you'll need to open your hard drive, then open the Applications folder, then look for the file DVD Player, and double-click it, and the movie will play. It's very rare for you to have to do anything more than pop the DVD in the drive.
So another possible meaning for "play movies on Apple computer" would be a movie you've downloaded off the Internet. There's a lot of different types of video files (video just means moving pictures, just like a movie) that are sent by email, or that can be downloaded off a web site.
If you want to play a movie or TV show you've bought from the iTunes Store, iTunes itself will play the movie using Quicktime. Quicktime is a program made by Apple for both their own Apple Mac computers, as well as for Windows PCs, and it comes automatically with iTunes.
Quicktime can play a lot of different types of video files, so it's one way to play movies on Apple computer. If you've got a movie file that you got by email, or that you saved from a website, Quicktime will probably play it, and it is already installed on every computer made by Apple.
There are exceptions, so if you can not play a video file (movie) when you double-click it, and Quicktime gives you an error message, then another option is the free VLC Player.
VLC Player is a free program that will play just about any type of video file you can get off the Internet, personally it's my favorite way to play movies on Apple computers. VLC Player is also available for Windows.
Lastly, if the person who asked how to "play movies on Apple computer" was talking about playing the movie on a web page, then again, Quicktime will work for a lot of these movies, and VLC might do the trick too (although I 've had problems in the past getting it to play movies that are "embedded" in web pages).
One of the most popular ways to put videos onto web pages is in Flash format. Flash Player is free, and comes already installed on most computers. As time passes, though, this looks likely to be replaced by "HTML5" which will let your web browser play videos without having to add Flash Player or any other extra "browser plug-ins".