The accumulated experience, the collected rake and tested functionality by time and hundreds of developers is the best way to describe the meaning of the libraries used in development.

There are pros and cons to using ready-made libraries:

• + You don’t have to spend time reinventing the wheel.
• + You have already tested the ready-made functionality and fixed “children’s problems” (if the library is popular).

1. The programmer is not always interested in how the library is vulnerable and affects performance.
2.  The module can be quite cumbersome if you only need to use a small part of the functionality.If you need just a couple of hours of work for implementation, it is often not justified to use ready-made solutions. When you can solve a massive task with a couple of lines of code and import it, there is no point in reinventing the wheel. It is important to initially understand and estimate the size of the intended functionality. This comes with experience.Some things can hardly be done without libraries (or at least they can be done, but they are difficult, long and don’t make sense). We are talking mostly about access to third-party tools and services. For example, the payment inside mobile applications is done through the standard, but still a library.

   The display of an image in the list can seem an easy task. But in fact, there will be some issues with caching, resizing, rounding corners, etc. This is a good example of when using popular image libraries is more than justified.