Buy Threshold Strips -

Best for a seamless look if you have hardwood floors. These can often be stained to match your exact floor color.

Best for connecting two hard floors of the same height (e.g., laminate to tile). The "T" shape hides the expansion gap between the two. buy threshold strips

Specifically designed for carpet-to-hard-floor transitions; it grips the carpet on one side and tucks under or over the hard surface on the other. Best for a seamless look if you have hardwood floors