A 5.1K ohm resistor is a standard electronic component that provides 5,100 ohms of resistance, commonly used for current limiting, pull-up/pull-down functions, and USB-C configuration lines.

Specifications

Resistance Value: 5.1KΩ (5,100 ohms)
Color Code (4-Band): Green (5), Brown (1), Red (Multiplier × 100), Gold/Silver (Tolerance) 
Power Ratings: Commonly available in 1/4 watt (0.25W) for standard low-power circuits, though 1/2W, 1W, and surface-mount (SMD) packages also exist. 
Tolerance: Typically ±5% (carbon film) or ±1% (metal film). 

USB-C Cables and Breakouts: Used on CC (Configuration Channel) pins in 5V pull-down applications to signal power requirements to USB-C controllers.
Circuit Design: Biasing transistors, signal processing, and acting as elements in voltage dividers