What, Why, & How to Open Source

What

Open Source describes a software license that ensures certain freedoms. There are 10 rules from the open source initiative

Open Source Software Analogies:

-free public schools (or OCW/iTunes) vs. pay as you go education

-free public libraries vs bookstores

-Wikipedia vs Britannica

Open Source in contrast to:

-Proprietary: commercial software that has restrictions on use, distribution, and modification.

-Freeware: There is no fee to use but you cannot study, modify, or redistribute.

-Shareware: Obtained free of charge for a certain amount of time then a payment is requested after the trial period.

-Public Domain: No laws restrict any use.

See also
-History of the Software Wars

-Wikipedia entries for Open source , Free Libre Open Source Software,  and  Freeware

Why

What kind of open are you looking for? Open examples besides software

Open Source: What It Is And Why You Should Care

Advantages of Open Source:

-Freedom to modify the software to your own needs.  Harness collective intelligence for collective invention through collaboration with developers around the world that increase the quality of the software.
-Frees you from vendor lock in (incompatible data, forced updates, or license renewals)
-It's free and decreases barriers to access

Disadvantages of Open Source:
-Lack the time to learn the software.
-May lack software of help resources (manuals, documentations, or community support)
-Lack of support, even though the application is free you may need to have pay the right person to administer and/or support it

Why People use Open Source Software:

-Cost: Free or "pay people not licenses"

-Commitment to openness and community

-stability

-Sustainability

-Security

-Intuitive design

-Flexibility/modularity

How

How to Find Free Open Source Software Alternatives  see also http://osliving.com/index.php 

69 Free or Open Source Tools For Students

List of Free/Open Source Software alternatives table , good categories

The Top 50 Proprietary Programs that Drive You Crazy — and Their Open Source Alternatives