しかも is a conjunction that adds another point, similar to 'moreover' or 'what's more' in English. It is often used when the second point is even more significant, surprising, or impressive than the first. It can connect two sentences or be used within a single sentence to add a second clause. For example, you might describe a person as smart, and then add that they are also kind, emphasizing the extra quality.

Unlike some conjunctions that require a specific verb form, しかも simply attaches to the end of a complete clause or sentence. It can follow a noun or adjective directly, or a verb in any tense. It is more common in written and formal spoken Japanese, but it is acceptable in everyday conversation when you want to make an emphatic addition. It is not as casual as それに, which has a similar meaning but is more conversational.

Punctuation is not mandatory, but in writing, a comma or period may precede it depending on the flow. In speech, a slight pause often occurs before しかも.