Single Candidate in a cell
Look at row A of the puzzle. Cell A4 is highlighted in blue, and candidate 3 is further highlighted in cyan. As you can see, the 3 is the only candidate in this cell, and must therefore be the solution for this cell. Other examples of Single Candidates can be seen at C1 and C2.

Puzzles which are created at difficulty level 1 can be solved completely using just this technique.