There are two basic types of computers: personal computers (PCs) made by different companies, and Macintosh computers which have a different internal and external appearance but can perform similar functions. Computers run using an operating system like Windows which controls how components interact and display information. Hardware components include the central processing unit (CPU), monitor, keyboard, mouse, speakers, and printer. Common storage media are floppy disks, CDs, and internal hard drives organized using folders and files. Popular software programs used in class include Word for documents, Excel for spreadsheets, PowerPoint for presentations, and Internet Explorer for web browsing.