This paper reviews the state-of-the-art performance of producible, 850-nm, current-guided GaAs/AlGaAs, top-emitting vertical-cavity surface-emitting lasers (VCSELs) and arrays. We focus on the flexibility of this technology platform in demonstrating a variety of devices and arrays. This includes a 99.8% device yield across a 3-in-dia. Metal-Organic Vapor Phase Epitaxy (MOVPE)-grown wafer and wavelength operation across approximately equals 100-nm range. Recent progress in device performance (Vth equals 1.55 V; Ith equals 0.68 mA; Pcw equals 59 mW; Tcw equals 200 degree(s)C, (eta) wp equals 28%) have and will enable great advances in VCSEL-array-based technologies. Included are unique ways of engineering modal characteristics from single-mode to quasi-incoherent emission. Array applications include 1D addressable arrays, particularly in the area of high-speed optical data links. An example application is the 32-channel-wide Optoelectronic Technology Consortium parallel links that have been operated error-free up to 980 Mbit/s (Manchester coded) through 100 m of bier. Two-dimensional matrix-addressable VCSEL arrays for processing and imaging applications will also be reviewed. Finally, we will discuss the exploitation of this VCSEL technology to explore the use of patterned or phased arrays of VCSELs. Their performance and relevant physics will be described, including the recent demonstration of in-phase coupling, watt-level emission, and multi-transverse-element mode coupling.