Soil salinity refers to the presence of high levels of salts in the soil, leading to a decrease in the soil's ability to support plant growth. Salinity can occur naturally in arid regions where evaporation rates exceed precipitation, or it can be caused by human activities such as irrigation with salty water or the use of fertilizers containing high levels of salt. High soil salinity can negatively impact plant growth by causing water stress, nutrient imbalances, and toxicity from specific ions like sodium and chloride. Research in this area focuses on understanding the mechanisms that contribute to soil salinity, developing strategies to manage and mitigate its impacts on agriculture, and identifying plant species or varieties that are more tolerant to saline conditions.