The real definition of open source software

If you think open source software is shareware 、 Free software and public domain software , Then you are not the only one who has this view .

When you hear “ Open source software open source” When the word , Do you think it has something to do with sharing software shareware、 Freeware freeware Or public domain software public domain Such terms are synonymous ？ If so , You are not the only one who has this view . Many people inside and outside the software industry believe that these terms are the same . This article explains the differences between these terms , Open source is a revolutionary licensing and development model . Share my experience with the above software , May be the best way to explore differences .

Shareware and freeware

As early as 1982 year , When I was there Apple II Plus On the use of BASIC When writing code , I started working as a computer programmer . I recall going to the local computer store in my hometown , And find the expensive floppy disk containing game and utility software in the plastic bag . please remember , This is from the perspective of a middle school student .

however , Some software can be obtained for free or at the lowest price . According to the specific license mode , It is called shareware or freeware . In shared software mode , You can only use the software for a certain period of time , If you find it useful , You are required to send the check to the author of the software .

however , Some sharing software actually encourages you to copy and provide it to your friends . This model is often called free software . in other words , The difference between the exact definition of shareware and freeware is very small , Therefore, it is easy to simply call the two together “ shareware ”. Although I'm not sure , But I don't remember whether I ever offered any software author the cost of using shared software , Mainly because I had no money when I was a teenager , But I definitely like using these software programs , And I learned a lot about computers .

Review the past , I now realize , If the software is provided under open source license terms rather than shared software terms , So as a new programmer , I could have learned a lot from growing up , And can achieve more . This is because few shareware will provide source code （ namely , Human readable software form ）. Shareware also includes license restrictions , The recipient is prohibited from trying to disclose its source code . If you cannot access the source code , It is difficult to understand the actual working mode of the software , Thus, it is difficult to expand or change its functions . This makes the end user completely rely on the original author of the shared software to make any changes or improvements .

Use shared software mode , It is almost impossible for any community of developers to influence code , And further innovate around the code . Redistribution and commercial use may also be further restricted . Although shareware may be free in terms of price （ At least it was free at first ）, But it is not free in terms of freedom , And you are not allowed to learn and innovate by exploring the internal principles of the code .

This leads to a big problem ： How is it different from open source software ？

The foundation of open source licensing

First , We need to understand “ Open source ” It refers to license mode and software development mode , Both are very different from shareware . In a way called non “ Left version ”copyleft Under the open source form of Open Source License , Provide users with key freedom rights , For example, there are no restrictions on accessing source code ; Can be sold for any purpose 、 Use or give away the software ; You can modify the software .

This form of license does not require payment of any royalties or license fees . Because the license is highly relaxed , It can be used without negotiation , A surprising result of this licensing model is its unique capabilities , It can make countless software developers work together to make new changes to the code 、 Useful changes and innovations . Even though technically , In this license mode, there is no need to provide source code , But almost everyone can use it to view 、 Study 、 Modify and distribute to others .

Not “ Left version ” Another aspect of open source licensing is , Any recipient of such software can add other license restrictions . This means the original author who licensed the code in this form , There is no way to prevent the recipient from further licensing to others under more restrictive terms . for example ：

Suppose the author Noah Wrote some software , And according to non “ Left version ” The open source license distributes it to the recipients Aviva. then ,Aviva Modified and improved Noah Software for , She has the right to rely on non “ Left version ” Open source license terms use the software . then ,Aviva You can decide to impose further restrictions on any recipients who may restrict the use of the software , For example, where or how to use it （ for example ,Aviva A limitation can be added , It is stipulated that the software can only be used in the following regions ： California , And it is not allowed to be used in any nuclear power plant ）. Even if Aviva You can access the source code , You can also choose never to publish the modified source code to others .

Unfortunately , Countless proprietary software companies use non “ Left version ” Open source licensed software . actually , Shared software programs can be restricted by adding shared software types （ for example , Cannot access source code or exclude commercial use ） To use non “ Left version ” Open source licensed software , Thus non “ Left version ” Open source license code is converted into shared software license mode .

Fortunately, , Many use non “ Left version ” Proprietary software companies that license open source software see the benefits of releasing source code . These organizations are generally organized through, for example GitHub Such software storage platforms provide modified source code to their recipients or the wider open source community , So as to continue to maintain the persistence of the open source model , Realize a virtuous circle of innovation . This is not entirely for charitable purposes （ Or at least not usually ）： These companies want to encourage community innovation and further improvement , So that they also benefit .

meanwhile , Many proprietary software companies do not choose to do this , This is also completely in line with non “ Left version ” Provisions of the open source license terms .

“ Left version ” Licensed open source software

1989 year , A new kind is called GNU General public permit （ Also known as GPL license ） The open source license of has been developed , Its purpose is to ensure that the software “ Born Free ”（ Like freedom of speech ）, And can always maintain this freedom , This and non “ Left version ” Open source licensed software sometimes happens differently . As a unique application of copyright law , Just follow these rules （ I will introduce it later ）,GPL Licenses ensure continuous software freedom . This unique application of copyright is called “ Left version ”copyleft.

And non “ Left version ” Like open source software ,“ Left version ” The license allows the recipient to use the software without restriction 、 Check the source code 、 Modify software , And further distribute the original or modified software to other recipients . And non “ Left version ” Open source licenses are different ,“ Left version ” Open source licenses require all recipients to have these same freedoms . Unless you don't follow the rules , Otherwise, these freedom rights can never be taken back .

send “ Left version ” Open source licenses can be enforced , And the reason for people to comply with the law is the application of copyright law . If “ Left version ” The recipient of the code does not comply with the license terms （ for example , Add any other restrictions on the use of the software or do not provide source code ）, Its license will be terminated , And because he no longer enjoys the legal license to use the software , He will become a copyright infringer . therefore , The “ Left version ” The free rights of any downstream recipient of the licensed software are guaranteed .

Beyond the basics ： Other software licensing modes

I mentioned public domain software earlier , Although it is often confused with open source software , But this model is different . Public domain software refers to the software that has taken steps to check and learned that there is no copyright corresponding to the software , The most common situation is that the software copyright expires or is abandoned by the author .（ In many countries / region , The copyright protection mechanism is not clear , This is why some public domain software may choose the open source license mode as an alternative .） No license is required to use public domain software . Although if the source code is available , Many people will think that public domain software is a form of open source software , But whether the public domain software becomes without a license “ Open source software ”, Is the subject of a lot of controversy .

Interestingly , There are many open source projects that use small modules of public domain software to achieve certain functions . There are even software that claims that the whole program belongs to the public domain , For example, the SQL Database engine is used in many applications and devices SQLite. Software without license terms is also very common .

Many people mistakenly believe that this unlicensed software is open source software , It belongs to the public domain , Or unlimited free use . In most countries （ Including the U.S. ）, The copyright of the software existed at the time of its creation . This means that you cannot use it without a license , Unless it gives up the copyright in some way , And put it in the public domain . There are some exceptions to this general rule , For example, implied license or reasonable use at the legal level . But in terms of how to apply them to specific situations , The situation is very complicated . With the intention of making it comply with the open source license terms , I don't recommend providing software without license terms , Because it leads to confusion and potential abuse .

The benefits of open source software

Like I said before , Open source is an efficient software development model , And has the great ability to promote innovation . But what does that mean ？

One of the benefits of the open source licensing model is that it greatly reduces the friction of innovation , Especially the innovation made by users other than the original author . This friction is limited , Because using open source software usually does not need to negotiate license terms , Thus greatly simplifying and reducing the use cost . In turn, , This creates an open source ecosystem , It encourages rapid modification and combination of existing technologies to form new things . These changes can usually be fed back into the open source ecosystem , Thus, an innovation cycle is constructed .

Drive a lot of things （ From your toaster to the Mars spacecraft ） Countless kinds of software running , It is the direct result of this ability to easily combine various programs —— Open source development mode makes all these software come true .