Pragmatics is the part of linguistics that is concerned with meaning in context. Language in real life use often works differently from what the formal theories of semantics would predict. An important part of pragmatics are the Gricean maxims, which are a set of rules that speakers follow to communicate effectively. The Gricean maxims are comprised of the following:

1)  Maxim of Quality: Make your contribution one that is true.
2)  Maxim of Quantity: Make your contribution as informative as necessary, but not more so.
3)  Maxim of Relation: Make your contribution relevant to the current conversation.
4)  Maxim of Manner: Make your contribution in a clear, brief, and orderly manner.

Sometimes, speakers violate one of the maxims intentionally to achieve a certain function. But sometimes, a violation can lead to failed communication. Consider the following situations and statements:

Situation 1:
John had a busy day. In the morning he was at school, in the afternoon he was at soccer practice. In the evening he calls his friend and tells him:
"Today, I played soccer and went to school."

Situation 2:
Grace goes to hand her friend Timothy a glass of water, but drops it. It shatters on the floor, so Timothy comments:
"Good job, Grace."

Situation 3:
Alec is a fan of mountain climbing, and last year he finally managed to make it to the top of Mount Everest. When he meets his old friend Clary, she asks if Alec has been up to anything exciting lately. Alec tells her:
"Last year, I tried to climb Mount Everest."