Acronym: Do It Yourself
Instead of letting others provide services to do the work for you for money, you can decide to do it yourself so that something new can be created that is original and self-made. DIY is considered to be a Good Thing similar to grassroots activism. One can decide to DIY for various reasons, even egoistical ones. Other reasons include to make a change for a better world or other improvement, to endanger a monopoly but also for profit, or to create one's own monopoly.
When people do it themselves as an alternative to commercial means the result is reduced labour costs and less taxation. When DIYing it is often useful to do some research, to read documentation and check HOWTOs so you don't have to re-invent the wheel, so to speak.
- Tweaking a hardware setup
- Instead of musicians walking to a big label, letting those label owners hiring people who work in a studio and who build it on CD et al, one can decide to do this themself. Lots of punk music was founded this way and eventually also indie rock, noise and other synthesized music.
- Instead of using a program and not being satisfied, one can decide to hack the source and add functionality. Or, to code a similar program which does what he or she wants to. This creates diversity and competition. OpenBSD was forked from NetBSD, then Theo started to create his own OS. The BSD license allowed him to do so. It also allowed the NetBSD developers to import Theo's code.
- The GPL was formed by RMS using a similar philosophy.