Textures / Particles non transparent when they should be

Hi, when i make a texture with a transparent back round, no matter what kind of format i save it in, when i import it into unity the only time the transparency is invisible is on a GUI. otherwise, its always either (where it should be transparent) green, black, or white the black around the outside. How do i make it so when i put it in an object or particle, the transparency is, well, invisible? Thanks you!

The material needs to use a transparency shader. In the material, click on the shader name, and select an equivalent shader in the "Transparent" submenu at the bottom. GUI shaders are already handling transparency by default.