What is the meaning of summation notation?

Summation notation is a mathematical shorthand used to represent the sum of a sequence of terms. It is typically denoted by the Greek letter sigma (Σ) and includes an index of summation, such as "i," along with lower and upper limits indicating the range of values for that index. For example, Σ (from i=1 to n) of a_i means to sum the terms a_1, a_2, ..., a_n. This notation simplifies the expression of large sums and is commonly used in mathematics, statistics, and computer science.