Altar and alter sound alike, but they do very different jobs in a sentence.
Altar is a noun. It refers to a table or raised place used in religious ceremonies. You will usually see it in church, temple, or wedding contexts. For example, They knelt at the altar.
Alter is a verb. It means to change, adjust, or modify something. It is used when something is being made different. For example, Please alter the schedule.
A simple way to remember the difference is this: if you need a thing or place, use altar. If you need an action, use alter.
- Altar: a sacred table or place
- Alter: to change something
- Correct example: The flowers were placed near the altar.
- Correct example: We had to alter the plan after lunch.
Because the words are pronounced the same, they are easy to confuse in writing. Checking whether you need a noun or a verb will usually lead you to the right choice.