Indoor and outdoor plants

When buying plants from my local supermarket i occasionaly see the label "indoor and or outdoor plant"

I dont understand this?

Two examples-pelargonium and impatiens-what your a probably looking at something that is not fully hardy-but is suitable as a houseplant or for growing outdoors-there are probably many others but these two spring to mind.

Plants that like warm conditions outside like during late spring/summer months, but need to be brought under cover during the rest.

Thank you for your replies. How does a plant become hardy in the first place?

All plants are hardy to a certain extent if you travel abroad you will see what we would class as unlikely plants for bedding schemes-have seen poinsettias in the Canaries used for that effect,

So it is not really the plant- it is the country it grows in that determines hardiness

Great pointers guys. Indoor plants can absorb harmful chemicals and improve air quality, making your home or office a more pleasant place to live or work. Different plants have different abilities to clean up different toxic substances. Before buying plants, try to find local plants for your environment. Even though the plant will be indoors, you don't want to select an invasive species. If you wander through a park, you can see the results of English Ivy and other invasive species have taken over some eco-systems. Read more here

All plants have evolved to fit their environment over time, but the ones we grow in our gardens, unless the pure species , have been bred for colour, fruit, longevity, pest resistance etc by nurserymen so some may have hardiness to a different country than their own built in.  If so, the label will tell you.  For instance Gardenias used to be conservatory plants only but now "Kleim's Hardy" will grow outside.