使用自由、開發自由、共享自由

使用者可免費下載使用，但不得任意更改程式內容，或作為商業用途。若需修改程式或作為商業用途，則需遵守開發者的授權聲明。
Users can download and use for free, but not allowed to change the content or use for commercial purposes. If you need to modify or use for commercial purposes, you must comply with the developer's authorization statement.

這兩種軟體的共通特性是：開發者或公司將軟體放在網站上供試用及推廣，使用上通常有時間限制或功能限制，若使用者有興趣，可付費擁有完整功能或長期的使用權。
The common feature of these two kinds of software is that the developer or company puts them on the website for trial and promotion. There is usually a time limit or function limit for use. If users are interested, they can have complete functions or long-term use rights by pay for it.

開發者於軟體發行同時附上軟體的原始程式碼，使用者不僅可以免費使用軟體，亦可根據自己的需求進行修改，是一種容許他人分享技術成果的開發方式。這一類的軟體，往往形成一個強大的社群力量，人人都可以是開發者、使用者、技術客服。最常見的例子：Firefox，因開放原始碼的緣故，許多方便的外掛程式紛紛被創造出來。
The developer attaches the original code of the software when released. Users can not only use the software for free, but also modify it according to their needs. It is a development model that allows to share technological results. This type of software often forms a powerful community force, and everyone can be a developer, or a user. The most common example: Firefox. Because of the open source code, many convenient plug-ins have been created.