The rules of Sudoku focus on the unique placement of digits 1-9 within rows, columns, and 3x3 boxes. The sum of each row is indeed 45, but this is a consequence of the rules, not a rule itself.

Scanning involves systematically checking rows, columns, and boxes to eliminate candidates from cells, which helps to narrow down the possibilities and reveal the correct numbers. It is not about guessing or filling all obvious numbers initially.

A 'Hidden Single' is when a digit can only appear in one cell within a row, column, or box, even if there are other candidates in that cell. Naked Pair, X-Wing, and Swordfish are more advanced techniques.

A 'Naked Pair' identifies two cells in a row, column, or box that contain only two possible digits, and those two digits are the same in both cells, allowing you to eliminate those digits from other cells in the same unit.

The X-Wing technique involves identifying two rows or columns where a digit can only appear in two cells, and these cells form a rectangle. This allows for the elimination of candidates from other cells in the same rows or columns.

The 'Unique Rectangle' pattern indicates that the puzzle might have multiple solutions, which is not allowed in a valid Sudoku. Therefore, it requires a specific technique to resolve the ambiguity.

In Sudoku, a 'candidate' is a possible number that could be placed in a cell, based on the rules of the game. It's not a number already placed or impossible, nor is it randomly selected.

A well-formed Sudoku puzzle must have a unique solution, which can be reached through logical deduction without guessing. Multiple solutions or no solution would make it invalid.

Pencil marking is used to note down all the possible candidates for a cell, which helps in visualizing the potential numbers and applying solving techniques. It's not about random filling, impossible numbers, or correct numbers.

A 'Naked Triple' involves identifying three cells in a row, column, or box that contain the same three candidates, which allows for the elimination of those candidates from other cells in the same unit.

The 'XY-Wing' technique involves three cells, each with two candidates, forming a specific pattern that allows for the elimination of a candidate from a fourth cell. It is not about triangles or rectangles.

A cell with only one possible candidate is known as a 'Naked Single'. It is a straightforward situation where the correct number can be placed immediately.

Forcing Chains is an advanced technique that involves analyzing chains of candidates across multiple cells to deduce the correct numbers. Scanning, Hidden Single, and Naked Pair are more basic techniques.

The 'Swordfish' technique is used to eliminate candidates in three rows or columns, based on a specific pattern of candidate placement. It is not about finding rectangles, hidden singles, or naked pairs.

The 'AIC' technique is an advanced method used to solve very difficult puzzles by linking candidates in a chain to deduce the correct numbers. It is not about simplifying puzzles or guessing.

In Sudoku, 'Uniqueness' refers to the requirement that the puzzle must have only one valid solution. Multiple solutions or no solution would make the puzzle invalid.

Randomly guessing numbers is not a valid strategy for solving Sudoku puzzles. The other options are all common and logical strategies used by solvers.

Coloring is used in advanced Sudoku solving to identify patterns and relationships between candidates, which helps in applying complex techniques. It is not about making the puzzle visually appealing or marking the correct or impossible numbers.

Backtracking is a method of undoing previous moves when a contradiction is found, which is a common technique in computer algorithms for solving puzzles. It is not about random filling or solving only specific difficulty levels.