In my experience, it is common for people to get confused when using ‘tact’ and ‘tack’.

Tact:

• a sense of (and an ability or will to use) the best and most considerate way to deal with people (so as not to upset them)
• skill in handling difficult situations or issues

Tack:

• a course of action or policy, or a way of dealing with a problem or situation
• a small, short sharp-pointed nail with a large flat head; to fasten something or fix in place with a tack or tacks
• to add something to an already existing whole – ‘to tack something on’
• a drawing pin (in North American English)
• a long loose temporary stitch used to fasten fabrics together; to sew something with long loose temporary stitches
• the riding harness for horses, including saddles and bridles
• the act of changing course by turning a boat’s head into and through the wind (creating a zigzag course to make progress against the wind); the boat’s course relative to the wind’s direction; the distance sailed between tacks
• a rope for securing a certain type of sail; the corner a rope is fastened to
• being sticky (as a quality or property)

Task:

• a specific piece of work to be done or undertaken
• an unpleasant or difficult job or duty
• to assign or give a job or piece of work to
• to make demands on someone’s resources or abilities
• to criticize or rebuke – ‘take to task’

Thank you to Johanna Levene aka Afthead for suggesting this post.