package - In R, what does "loaded via a namespace (and not attached)" mean?

Question

In R, what does it mean for a package to be "loaded via a namespace (and not attached)" in sessionInfo()?

Edit:

For example:

> sessionInfo()

R version 2.15.2 (2012-10-26)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

---->>>> loaded via a namespace (and not attached):
---->>>> [1] tools_2.15.2

Answer 1

It means the package (In this case R) can access the package functions/objects, but the user can not without explicitly loading the tools package where as stats, graphics, etc. are loaded and ready to go for the user.

Here's an example:

sessionInfo()
file_ext("file.com")
tools::file_ext("file.com")
sessionInfo()