Carpet in a house is rarely one single piece. More often it is made of several strips that are spliced together. When done properly the splice lines are invisible, creating the illusion of a solid carpet surface. Splicing two pieces of carpet is accomplished with the use of a seaming iron and seaming tape. Both of these items are available at your local hardware store. If you have never spliced carpet before, practice on a few remnants first.

...
The seam of a properly spliced carpet is invisible.

Step 1

Line up the two pieces of carpet. If the edges are not perfectly straight, overlap one on top of the other slightly. Use a sharp knife to trim the edge of the lower piece, using the edge of the upper piece as a guide.

Step 2

Lay a strip of hot-melt seaming tape under the seam created by the two pieces of carpet. The seam should run down the middle of the tape.

Step 3

Turn on the seaming iron and give it time to heat.

Step 4

Hold the sections of carpet open and press the iron against the tape at the beginning of the seam. Let it sit for 30 seconds.

Step 5

Begin sliding the iron slowly forward, heating the tape as you go. Have a second person press the two pieces of carpet together into the hot tape behind the iron, creating as tight a joint as possible.

Step 6

Continue ironing the tape and splicing the carpet until the seam is complete.

Step 7

Sew the two halves together using a curved needle and fishing line if the splice is in a particularly high-traffic area. Keep the stitches as small as possible to prevent them from being noticed.

Step 8

Roll a carpet tractor over the seam to blend the carpet from both sides together.