A turbine blade comprising: an airfoil comprising an outer wall formed by a pressure sidewall and a suction sidewall joined at a leading edge and at a trailing edge, a blade tip at a first end and a root at a second end opposite the first end for supporting the blade and for coupling the blade to a disc, wherein the blade tip comprises: a tip cap extending between the pressure sidewall and the suction sidewall, a squealer tip wall extending outward of the tip cap and extending along a direction from the leading edge to the trailing edge, the squealer tip wall comprising a forward surface that is continuous with an outer surface of the pressure sidewall, wherein an outward direction leads away from the second end, and a plurality of cooling channels spaced apart along a contour of the squealer tip wall, each cooling channel comprising: an inlet configured for receiving a coolant from airfoil internal cavity, an upstream section comprising a closed channel extending from the inlet to the forward surface of the squealer tip wall, a downstream section comprising an open channel formed by a slot on the forward surface of the squealer tip wall, the slot extending outward in a downstream direction so as to guide the coolant along the forward surface toward a outermost tip of the squealer tip wall, characterized in that the blade tip comprises an outward step at a pressure side edge of the tip cap, wherein the squealer tip wall extends outward from said step to said outermost tip, and wherein the blade tip further comprises a plurality of chord-wise spaced apart cooling holes formed through the step which are in fluid communication with an airfoil internal cooling system. an airfoil comprising an outer wall formed by a pressure sidewall and a suction sidewall joined at a leading edge and at a trailing edge, a blade tip at a first end and a root at a second end opposite the first end for supporting the blade and for coupling the blade to a disc, wherein the blade tip comprises: a tip cap extending between the pressure sidewall and the suction sidewall, a squealer tip wall extending outward of the tip cap and extending along a direction from the leading edge to the trailing edge, the squealer tip wall comprising a forward surface that is continuous with an outer surface of the pressure sidewall, wherein an outward direction leads away from the second end, and a plurality of cooling channels spaced apart along a contour of the squealer tip wall, each cooling channel comprising: an inlet configured for receiving a coolant from airfoil internal cavity, an upstream section comprising a closed channel extending from the inlet to the forward surface of the squealer tip wall, a downstream section comprising an open channel formed by a slot on the forward surface of the squealer tip wall, the slot extending outward in a downstream direction so as to guide the coolant along the forward surface toward a outermost tip of the squealer tip wall, a tip cap extending between the pressure sidewall and the suction sidewall, a squealer tip wall extending outward of the tip cap and extending along a direction from the leading edge to the trailing edge, the squealer tip wall comprising a forward surface that is continuous with an outer surface of the pressure sidewall, wherein an outward direction leads away from the second end, and a plurality of cooling channels spaced apart along a contour of the squealer tip wall, each cooling channel comprising: an inlet configured for receiving a coolant from airfoil internal cavity, an upstream section comprising a closed channel extending from the inlet to the forward surface of the squealer tip wall, a downstream section comprising an open channel formed by a slot on the forward surface of the squealer tip wall, the slot extending outward in a downstream direction so as to guide the coolant along the forward surface toward a outermost tip of the squealer tip wall, an inlet configured for receiving a coolant from airfoil internal cavity, an upstream section comprising a closed channel extending from the inlet to the forward surface of the squealer tip wall, a downstream section comprising an open channel formed by a slot on the forward surface of the squealer tip wall, the slot extending outward in a downstream direction so as to guide the coolant along the forward surface toward a outermost tip of the squealer tip wall, characterized in that the blade tip comprises an outward step at a pressure side edge of the tip cap, wherein the squealer tip wall extends outward from said step to said outermost tip, and wherein the blade tip further comprises a plurality of chord-wise spaced apart cooling holes formed through the step which are in fluid communication with an airfoil internal cooling system.