Software license.

• BSD: It is a software license, it is free being so close to the public domain, it allow use the source.
• GNU/LGPL: It is a software license, similar to the GNU, but there aren't allow acts apart copy, distribute or manipulate it.
• GNU: It is the most frequently used software license. It allow to manipulated, use, study and copy it.It is the first copyleft license for general use.
• MPL: It is a open source software license, it belogs to Mozilla.
• Multilicense is distributing software under two or more different sets of terms and conditions.

FREE SOFTWARE

There are different types of free software:

• Freeware: Are applications free and you can distribute them as you like.
• Shareware: Are applications you can distribute them as you like but they are limited.
• Careware: Applications that cost more because some of money goes to charities.
• Public Domain: When the author of a program dies, the program becomes a free software what can be manipulated for everybody, It can be an authorless program.
• Open source: Everybody can access to source an manipulate it.
• Copyleft: You can copy it without asking author.
• Property: It is about who belongs a program.

Introducing Computer Science

PC is a personal computer, it is make by software and hardware, software is the things you can't touch, programs; instead, hardware is everything you can touch, like CPU (which keeps microprocessor, ventilators, cards like graphics card...), screen, keyboard, mouse... Software makes we can understand language of computer because when you type a letter on the keyboard, it understand it like 0 and 1, what is called binary code, then, software 'translate' it into source wich in some operating systems like Linux or Ubuntu can be manipulated by programmers. Finally source is 'translate' again so that user can understands it and it is shown in interface.


There are different types of operating systems. There are some of them that are free and they can be manipulated, like I said before, but there are some that can't be manipulated like Windows or Mac Os, which have a default source. Operating systems that can be manipulate are more sensitive to the virus.