Coilde Tubing: A coiled tubing string manufactured with a constant outside diameter and variable wall thicknesses within the length of the spooled tube. The tapered string may be constructed (1) as a continuously-milled string incorporating multiple, single wall thickness skelp segments joined using skelp-end welds, (2) as a continuously-milled string incorporating single wall thickness skelp segments with continuously-tapered skelp segments joined using skelp-end welds, or (3) continuously-milled coiled tubing segments of single wall thickness joined to other finished tube segments of increased wall thickness using the tube-to-tube welding process. Jointed: A string of tubing assembled for deployment into the wellbore with segments of the string comprised of tubing joints having either a variable ID, variable OD, or both.