Where filters a sequence of values based on a predicate.
Example
Select DataTable rows with where.
DataTable dt = new DataTable();
dt.Columns.Add("name", typeof(string));
dt.Rows.Add("john");
dt.Rows.Add("dan");
var filteredRows = dt.Rows
.Cast<DataRow>()
.Where(r => r["name"] == "dan").ToList();