The paper presents a detailed characterization of the LIGO detectors during their sixth science run (S6), which took place from July 2009 to October 2010. The LIGO detectors, located at Hanford and Livingston observatories, operated as part of a global network with Virgo and GEO600 to search for gravitational waves (GWs) of astrophysical origin. The sensitivity of these detectors was limited by noise sources inherent to the instrumental design and their environment, which could couple into the GW readout. The study reviews the performance of the LIGO instruments during this period, the work done to characterize the detectors and their data, and the impact of transient and continuous noise artifacts on the sensitivity of LIGO to various astrophysical sources. The LIGO detectors were configured with improvements to enhance their sensitivity and to prototype upgrades for the second-generation Advanced LIGO (aLIGO) detectors. These improvements included increasing the input laser power, installing a CO₂ laser thermal-compensation system, and implementing a new homodyne detection system with an output mode cleaner. Additionally, seismic feed-forward systems were improved to combat higher levels of seismic noise at the Livingston observatory. The sensitivity of the LIGO detectors during S6 was evaluated based on their ability to detect GWs from various sources, including compact binary coalescences (CBCs), short-duration GW bursts, and a stochastic GW background. The performance of these analyses was measured by the searched volume of the universe multiplied by the searched time duration. However, long and short duration artifacts in the data, such as narrow-bandwidth noise lines and glitches, further restricted the sensitivity of GW searches. The paper also discusses data-quality problems encountered during S6, including seismic noise, seismically-driven length-sensing glitches, and upconversion of low-frequency noise due to the Barkhausen effect. These issues were addressed through various mitigation strategies, including the implementation of seismic feed-forward systems and the use of data-quality vetoes to remove data likely to contain noise artifacts. The results of this study highlight the improvements in detector stability and sensitivity during S6, which significantly increased the searchable volume of the universe for astrophysical analyses. The work described in this paper follows from previous studies of LIGO data quality during Science Runs 5 and 6, and similar studies have been performed for the Virgo detector. The findings provide valuable insights into the performance of the LIGO detectors and their data during S6, and they contribute to the ongoing efforts to improve the sensitivity and reliability of gravitational wave detection.The paper presents a detailed characterization of the LIGO detectors during their sixth science run (S6), which took place from July 2009 to October 2010. The LIGO detectors, located at Hanford and Livingston observatories, operated as part of a global network with Virgo and GEO600 to search for gravitational waves (GWs) of astrophysical origin. The sensitivity of these detectors was limited by noise sources inherent to the instrumental design and their environment, which could couple into the GW readout. The study reviews the performance of the LIGO instruments during this period, the work done to characterize the detectors and their data, and the impact of transient and continuous noise artifacts on the sensitivity of LIGO to various astrophysical sources. The LIGO detectors were configured with improvements to enhance their sensitivity and to prototype upgrades for the second-generation Advanced LIGO (aLIGO) detectors. These improvements included increasing the input laser power, installing a CO₂ laser thermal-compensation system, and implementing a new homodyne detection system with an output mode cleaner. Additionally, seismic feed-forward systems were improved to combat higher levels of seismic noise at the Livingston observatory. The sensitivity of the LIGO detectors during S6 was evaluated based on their ability to detect GWs from various sources, including compact binary coalescences (CBCs), short-duration GW bursts, and a stochastic GW background. The performance of these analyses was measured by the searched volume of the universe multiplied by the searched time duration. However, long and short duration artifacts in the data, such as narrow-bandwidth noise lines and glitches, further restricted the sensitivity of GW searches. The paper also discusses data-quality problems encountered during S6, including seismic noise, seismically-driven length-sensing glitches, and upconversion of low-frequency noise due to the Barkhausen effect. These issues were addressed through various mitigation strategies, including the implementation of seismic feed-forward systems and the use of data-quality vetoes to remove data likely to contain noise artifacts. The results of this study highlight the improvements in detector stability and sensitivity during S6, which significantly increased the searchable volume of the universe for astrophysical analyses. The work described in this paper follows from previous studies of LIGO data quality during Science Runs 5 and 6, and similar studies have been performed for the Virgo detector. The findings provide valuable insights into the performance of the LIGO detectors and their data during S6, and they contribute to the ongoing efforts to improve the sensitivity and reliability of gravitational wave detection.