What counts as a lead source
The list of lead source types is the easy part. You could memorise it in a minute. The category is also where most attribution quietly dies, because “Paid search” is a label, not a budget decision. So here is the list, and then the more useful half: why the label on its own is never enough.
A lead source is the marketing channel, campaign, or referrer that brought a prospect to you, the answer to “where did this person actually come from.” For the full definition, see what a lead source is.
The standard categories
Tools name them slightly differently, but the set is consistent. Google’s own analytics documentation defines most of these channels the same way.
Found you via an unpaid search result (Google, Bing).
Clicked a paid search ad (Google Ads, Microsoft Ads).
Typed your URL or used a bookmark, with no referrer detected. Often a catch-all for sources the system could not see.
Followed a link from another site (a blog mention, a directory, a partner page).
Clicked a link in an email (newsletter, campaign, transactional).
Followed a link from a social network (LinkedIn, Facebook, X, Reddit, YouTube).
Clicked a paid ad on a social network (LinkedIn Ads, Meta Ads).
Came via a tracked partner link, usually with a unique code in the URL.
Podcast mentions, conferences, offline campaigns, anything that fits nowhere else.
Why the category alone isn’t enough
Knowing a lead is “Paid search” tells you almost nothing you can act on. You cannot cut a category; you fund and cut specific campaigns. The useful unit is one level deeper: not “Paid search” but “Local Services Sydney,” not “Social” but the specific post or video that drove the click.
There is a second problem with trusting the category: the most common one is frequently wrong. “Direct” is what gets recorded when the system cannot see the real source, and that happens constantly. A SparkToro experiment found analytics logged 100% of real visits from TikTok, Slack, Discord, WhatsApp and Mastodon, and 75% of Facebook Messenger visits, as Direct (2023). So a big slice of your “Direct” bucket is not direct at all; it is sources that were lost. Reporting by category alone bakes that error in. Getting from category to campaign, accurately, is the subject of lead source attribution. So treat the type as the first word of the answer, never the whole of it: useful only once you can name the specific campaign underneath and trust that the category was recorded correctly in the first place.
B2B versus B2C differences
The categories are the same; the weighting and the journey differ. B2C tends to be shorter and more single-touch: someone sees an ad, clicks, buys, often in one session, so first and last touch are closer together. B2B is longer and multi-touch: a prospect reads something on LinkedIn, comes back via search weeks later, downloads a guide, then fills in a form after a colleague forwards it. More sessions, more devices, more chances for the original source to be lost along the way, which is exactly why B2B needs source capture that persists across the whole journey rather than a single snapshot at submit.
How to capture each type accurately
Whatever the type, accurate capture is the same discipline: record the source the moment the visitor arrives, hold it first-party across the visit, and attach it to the form at submission, server-side, so it survives referrer stripping and lost UTMs. That single method handles every category above, paid and organic, search and social, without per-channel configuration. The walkthrough is in how to track lead sources, and the mechanism in the product is on how Lead Source works.
The list of types is worth knowing. But the money is in the level below it: the specific campaign, captured accurately, tied to whether the lead became a customer.