An altar is a table or raised surface used in a religious ceremony. To alter something is to change it. These homophones do different jobs. Altar is a noun and alter is a verb. These parts of speech can help you choose the spelling.
Choose altar for a ceremonial object
The couple stood near the altar during the ceremony. Here altar names a place within the room. In They placed flowers on the altar, it names the surface that holds the flowers.
Choose alter for a change
The tailor will alter the jacket sleeves. The verb describes changing how the sleeves fit. You can also alter a schedule by changing its timing. Try replacing the word with change. If the replacement fits, alter is the spelling you need.
