> LGPL is a regular license, it is not a viral license.
> GPL is a viral license.
The LGPL's level of "virality" is small, but nonzero - it imposes requirements on a larger program of which you use LGPL code as a part. Those requirements are much smaller than the requirements imposed by GPL code in the same circumstances, but they are real, and much more substantial than e.g. including a copyright notice.
> The GNU glibc uses LGPL and almost any program run on a Linux system uses glibc, regardless in what programming language it has been written, at least for the system calls.
glibc has an explicit linking exception for programs using its public interface.
> GPL is a viral license.
The LGPL's level of "virality" is small, but nonzero - it imposes requirements on a larger program of which you use LGPL code as a part. Those requirements are much smaller than the requirements imposed by GPL code in the same circumstances, but they are real, and much more substantial than e.g. including a copyright notice.
> The GNU glibc uses LGPL and almost any program run on a Linux system uses glibc, regardless in what programming language it has been written, at least for the system calls.
glibc has an explicit linking exception for programs using its public interface.