Here's a breakdown:

* Elements or radicals: These are the building blocks of compounds. Elements are found on the periodic table, while radicals are groups of atoms that act as a single unit.

* Change places: This means that the positive and negative parts of two reactants switch partners.

* Formation of new compounds: As a result of this exchange, two new compounds are formed.

General formula:

```

AB + CD → AD + CB

```

Example:

Silver nitrate (AgNO₃) reacts with sodium chloride (NaCl) to form silver chloride (AgCl) and sodium nitrate (NaNO₃).

```

AgNO₃ + NaCl → AgCl + NaNO₃

```

Key characteristics of double displacement reactions:

* They often occur in aqueous solutions.

* They involve the formation of a precipitate (solid), a gas, or a weak electrolyte (substance that doesn't conduct electricity well).

Let me know if you'd like more examples or explanations!