Conversions are Desired actions, that users perform on a website, in a newsletter or in a campaign.

In short:
A conversion happens when someone does what you want to achieve.

Typical conversions:

• Purchase in an online store
• Send contact form
• Subscribe to newsletter
• Request a quote
• Phone call
• Download (PDF, Whitepaper etc.)

Why are conversions so important?

• They show whether marketing really brings results
• Clicks alone are not enough - conversions bring value
• They are the basis for sales, leads and growth

Conversion Rate (CR): $\text{Conversion rate}=\frac{\text{Conversions}}{\text{Visitors:inside}}\times 100$

Example:
200 visitors, 10 inquiries
→ Conversion rate = 5 %

Conversions in online marketing:

• Google Ads: Purchase, inquiry, call
• SEO: Same goals, but without advertising costs
• Newsletter: Click, register, purchase
• Landing pages: Focus often on exactly one conversion

Mnemonic:
CTR brings visitors:inside - Conversions bring results.

Perhaps also interesting:

• Micro vs. macro conversions

Interested in other topics? Here we have a few more suitable explanations.