Why Not Just Make Programs Self-Contained?

[skylerclooney]

Hey everyone,
I’m Skyler, new here. A few days ago I had my first proper encounter with DLL problems, and it honestly threw me off. I was trying to run a small utility I downloaded, but instead of starting, it complained about a missing `api-ms-win-crt-runtime-l1-1-0.dll`. I had no idea what that even meant.
After some digging, I figured out that DLL files aren’t just 'extra files,' they’re more like shared libraries Windows programs call on when they need certain functions. I ended up repairing my system files and reinstalling some runtimes, which solved it, but the whole thing left me with a question I can’t quite answer:
Why does Windows prefer using these shared DLLs instead of just including everything the program needs in one self-contained package? To me it feels like having a program depend on external files makes it more fragile. Is there an actual benefit I’m not seeing, beyond saving disk space?

[bagelruffled]

DLLs let Microsoft (or developers) update a library independently of the programs that use it. For example, if a security patch is needed, updating the DLL fixes the issue for every program that relies on it.

[nikolasalexander1]

That’s a great point by bagelruffled! Another huge reason Windows prefers shared DLL files over self-contained packages is system memory and resource efficiency.

Back in the day, storage and RAM were very limited. If 10 different games or apps all needed the exact same DirectX or Visual C++ functions, and each program carried its own copy, it would waste massive amounts of disk space and duplicate RAM usage. By sharing one single DLL file in the system, multiple programs can use it at the same time without slowing down the PC.

Even today with huge hard drives, it keeps the operating system much cleaner and organized!