Custom Markers are a way for you to annotate your maps with additional information by marking significant spots.

Here's what they look like on a map:

Double-click on one with your left mouse-button, and you will be shown that Custom Marker's full information:

This particular Marker has an image attached to it.  Markers can have images, Snapshots, or web links attached to them to help flesh out any information that's been entered.

Double-click on one of the images to enlarge it, and see any additional information that the creator of this Marker has entered about it:

Here's another marker.  This time, let's take a closer look at all the information that can be packed in:

1. Submitter Information - Who created this Custom Marker?  This section show the name, user profile picture (upload yours today!), and hometown of the user who submitted this marker.
   
2.  Modification Buttons - If the marker is viewed by its creator, they will have the option of moving, editing, or deleting the Custom Marker. (click here to learn how)
   
3. Title/Caption - A descriptive title meant to convey why this marker is here and what it signifies.
4. Date/Date Range - When the events or information described by the marker happened or were relevant.
5. Certainty Level - Relates how certain the author of the marker is concerning the accuracy of the information they are presenting. (1-10, 10 being absolutely certain)
6. Attached Snapshots - Links this marker to other locations in the HistoryGeo map library that are related to this marker in some way.
7. Attached Web Links -  These can be used to point users to other relevant sources, external image galleries, etc...
8. Description - The full rundown of what this marker is here to represent.
   
9. Marker Type - A marker's type is meant to briefly illustrate what a point represents on a map without having to read the title or description.
   

There's a Snapshot attached to this Marker:

If you click the "Go" button, you will see be asked if you want to leave the current map.  If you're not done looking at the current map, then click "No."  If you're done looking at the current map and still wish to go to the marker's snapshot, then click "Yes."