## Overview

Kevel offers four ad code options: Synchronous, Asynchronous, Email, and 3rd Party Ad Server.

## Ad Code Options

**Standard (Asynchronous)** code is our standard code. It loads ads independently of the rest of the page, so it won't slow down page loads. It is a JavaScript tag, with an HTML div that loads the placement from the JavaScript. When a web page loads with asynchronous ad code, the code indicates to the browser to continue loading everything else on the page while it waits for the creative from Kevel.

**Synchronous** code loads on a page like it normally does: line by line, waiting for element. It can potentially slow down page loads, especially if the synchronous code is serving third-party ads that pass impressions from one server to another.

**Email code** consists of a static link and static image tag. It can only serve images, and not Flash or JavaScript/HTML creatives. This means it cannot serve tags from other networks. Only use email code if other options aren't available.

**3rd Party Ad Server** code is useful if you are serving Kevel ads through another server (such as DFP), or if you need to serve ads to a platform where HTML cannot be used. Note that 3rd Party Ad Server code cannot be used with companion ads or other distribution options.

## Ad Code Components

All Standard ad tags contain a comment that explains what the code loads:

```javascript
/* load placement for account: NetworkName, site: SiteName, size: 160x600 - Wide Skyscraper*/
```

The `ados_add_placement()` function loads the actual placement:

```javascript
ados_add_placement(1613, 15404, "azk57720", 6);
```

The first number is your **network ID**. The second is the **site ID**. The string is the name of the placement. Kevel generates this string randomly. This placement name must match in both the script and the `<div>`. The last number is the **adType ID**.

Updated 10 months ago

### What’s Next

- [Generating Ad Code](https://dev.kevel.com/docs/generating-ad-code-1)  
- [Modifying the Ad Code](https://dev.kevel.com/docs/modifying-the-ad-code)  
- [VAST Ad Code](https://dev.kevel.com/docs/vast-ad-code)