The Vivado Design Suite uses design constraints to define requirements for both the physical and timing characteristics of the design.
For more information, see Guiding Implementation with Design Constraints.
The read_xdc command reads an XDC
constraint file, then applies it to the in-memory design.
Tip: Although Project Mode supports the definition of constraint sets, containing multiple
constraint files for different purposes, Non-Project Mode uses multiple
read_xdc commands to achieve the same effect.