Along the side; by the side; side by side with.
"The small boat raced alongside the large cruise ship as they both moved down the river."
In plain English: Alongside means doing something at the same time as someone else is doing it nearby.
"The students sat alongside during the lecture to take notes together."
Usage: Use alongside to indicate that two people or things are positioned next to each other, often implying cooperation rather than just physical proximity. It is frequently confused with "beside," but while both describe location, alongside suggests a shared context or joint effort more strongly.
Together with or at the same time.
"She decided to launch her new business alongside her full-time job."
The word alongside is formed by combining the words along and side. It entered English as a compound phrase to describe being positioned next to something else.