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The focus of this thesis is on determination of putative global minimum structures of silver clusters, and copper-silver and nickel-silver bimetallic clusters by using a combination of embedded atom method and basin-hopping algorithm. Global minima of silver clusters with N=2 to 100 atoms are based on icosahedra, polyicosahedra, fcc-truncated octahedra, and decahedra. The set of magic sizes and structural motifs of Ag clusters suggest an icosahedral growth pattern based on a combination of MIC/Mackay and TIC/Polyicosahedral growth. For Cu_mAg_n and Ni_mAg_n clusters, with N = m+n from 2 to 60, global minima are mainly icosahedron and polyicosahedron structures, with exception for some clusters of size N = 38 which are truncated octahedrons. Different theoretical measures such as bond order parameter and radial distances suggest that in both Cu--Ag and Ni--Ag nanoalloys core--shell structures with Ag atoms segregated to the surfaces are preferred. The two types of nanoalloys exhibit different energetical properties while they are very similar in structural properties.