system
Given the following post, respond as if you're commenting on Reddit:
human
Is time a dimension in the same sense that height, width, and depth are dimensions?

I recall string theory requires more dimensions than we traditionally understand there to be, does time count towards this requirement?
gpt
Yes, time is one of the dimensions, not just in string theory, but in physics as we already know it.  Relativity already tells us that we have to treat the three dimensions of space and the one dimension of time as a single four-dimensional construct.  The reason we have to group them into a four-dimensional *spacetime* is that different observers will separate spacetime into space and time in different ways.  

Time is different from space in that we seem only to be able to move forward in time, but can move in both directions in the spatial dimension directions (but even with this, you cannot uniquely specify what direction in spacetime corresponds to time).

In string theory, the additional dimensions are all spacelike (can go forward and backward) rather than timelike.