Should an index be created for each column in a database table?

Creating an index for each column in a table is not recommended. Indexes speed up data search and retrieval, but they also increase insert, update, and delete times, and occupy additional disk space. It is better to create indexes only on columns that are frequently used in WHERE conditions, JOINs, or for sorting (ORDER BY). The optimal approach is to analyze queries and create indexes purposefully to improve performance without unnecessary costs.