Once you have created an index in Access, you don't have to worry about it again. Disadvantages are that processing is slowed, especially if you have many indexes. Every time you add or delete a record, the system must update all pointers. In Access, an index is automatically created for the primary key. You may have up to 32 indexes per table.
Indexes are properties of fields.
Additionally, you choose whether the index may include duplicates or not. The name of the index will be the same as the name of the field. To index on multiple fields, use the Index tool. Give the index a name and choose all the fields making up the index. Here is an example showing the Index tool.