Summation notation is a shorthand way to represent the sum of a series of numbers. The symbol "Σ" is used to indicate that we are adding up all the terms in the series.
A series refers to the collection of terms being added together in summation notation.
Upper Limit and Lower Limit: In summation notation, there are usually upper and lower limits written above and below the Σ symbol, indicating which terms should be included in the sum.
Index Variable: The index variable represents which term position we are currently adding in summation notation. It can be any letter or symbol chosen by convention.