Spacing between custom command and subsequent text

Question

I have defined a custom command for the name of my project; e.g. \newcommand{\projectname}{Gizmo}. When I used the command in my document, I've found that I need to place a ~ after the command in order to provide a space between the command and the text that follows.

For example in my tex document,

The \projectname is on track.

Produces the following pdf output:

The Gizmois on track.

So I have to use a tilda as follows:

The \projectname~is on track.

Which now produces the correct pdf output:

The Gizmo is on track.

Would someone please clarify what is going on and what is the correct (best practice) for dealing with this situation.