An algorithm is a set of instructions that are followed to solve a problem or complete a task. The characteristics of an algorithm include: 1. Finiteness: An algorithm must have a finite number of steps that will eventually lead to the solution of the problem. It cannot go on indefinitely. Example: To sort a list of numbers in ascending order, we can use the bubble sort algorithm. The algorithm will compare adjacent elements in the list and swap them if they are in the wrong order. This process is repeated until the list is sorted. 2. Definiteness: Each step in the algorithm must be well-defined and unambiguous. There should be no room for interpretation or confusion. Example: To find the area of a rectangle, we can use the formula A = l x w. Here, l and w represent the length and width of the rectangle, respectively. The formula is well-defined and unambiguous. 3. Input: An algorithm must take input from the user or from another program to solve the problem. Example: To calculate the sum of two numbers, we need to take input from the user for both numbers. 4. Output: An algorithm must produce output after completing the steps to solve the problem. Example: To calculate the sum of two numbers, we need to output the result of the addition. 5. Effectiveness: An algorithm must be effective in solving the problem. It should not be too complex or inefficient. Example: To search for an element in a list, we can use the linear search algorithm. However, if the list is too large, this algorithm may be too slow and inefficient. In such cases, we can use more advanced algorithms like binary search. In summary, an algorithm is a set of well-defined instructions that take input, produce output, and solve a problem effectively and efficiently.