# Make programs easy to change

Referenced in:

Programmers spend a lot of time changing programs that they, or other programmers, have already written. Up to 90% of their time, in some studies.

Make code easy to change. That means:

• Easy to understand.
• Easy to reuse.
• Easy to test.

Things to do:

• Comments. Explain the patterns you're using, the parameters of your Subs, what you were thinking when you designed the code, your favorite joke…
• DRY.
• Meaningful variable names.
• Good indenting.