Generally, when two or more words come before a noun, modifying it, and act as a single idea, we called the result an attributive compound adjective. These are hyphenated.

Examples:

A red-hot iron bar
Some freshly-baked cakes

When a compound adjective follows a noun, we call it a predicative compound adjective. We do not hyphenate these.

The iron bar is red hot.
These cakes are freshly baked.

Hyphens between words (Grammarbook.com)

To hyphenate or not to hyphenate (Editors Group)

Generally, when two or more words come before a noun, modifying it, and act as a single idea, we called the result an attributive compound adjective. These are hyphenated.

Examples:

A red-hot iron bar
Some freshly-baked cakes

When a compound adjective follows a noun, we call it a predicative compound adjective. We can choose not to hyphenate these. To do so is a matter of style, and can be advisable if ambiguity is possible.

The iron bar is red hot.
These cakes are freshly baked.

Hyphens between words (Grammarbook.com)

To hyphenate or not to hyphenate (Editors Group)

Generally, we hyphenate two or more words when they come before a noun they modify and act as a single idea. This is called a compound adjective.

Examples:

A red-hot iron bar
Some freshly-baked cakes

When a compound adjective follows a noun, a hyphen is usually not necessary.

The iron bar is red hot.
These cakes are freshly baked.

Hyphens between words (Grammarbook.com)

Generally, when two or more words come before a noun, modifying it, and act as a single idea, we called the result an attributive compound adjective. These are hyphenated.

Examples:

A red-hot iron bar
Some freshly-baked cakes

When a compound adjective follows a noun, we call it a predicative compound adjective. We do not hyphenate these.

The iron bar is red hot.
These cakes are freshly baked.

Hyphens between words (Grammarbook.com)

To hyphenate or not to hyphenate (Editors Group)