> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kinetica.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Graph Concepts

A graph typically comprises [nodes](/content/graph_solver/network_graph_solver#graph-nodes),
[edges](/content/graph_solver/network_graph_solver#graph-edges), [weights](/content/graph_solver/network_graph_solver#graph-weights), and
[restrictions](/content/graph_solver/network_graph_solver#graph-restrictions), but only requires *edges* and
*weights*. The graph created in this tutorial only uses *edges* and *weights*.

In this particular example, *edges* are logically mapped to sections of roadways
and footpaths throughout the Washington, D.C., area. Each *edge* corresponds to
a consecutive pair of points from each of the source LINESTRINGs, so a
LINESTRING containing *n* points will have *n-1 edges*. Because
the source graph is not created with *nodes*, implicit *nodes* are assigned
at either end of each *edge* after graph creation.

For example, link ID `18350083` is a part of the Ward Circle roundabout, which
itself is part of Massachusetts Avenue Northwest near American University.
Selecting link ID `18350083` from the `dc_shape` table reveals the following WKT
linestring (the end of the linestring was removed for clarity):

```
LINESTRING (-77.08544159 38.93787003, -77.08544159 38.93793869, -77.08545685 38.9380188, -77.08548737 38.9381218, ...)
```

As noted above, each consecutive pair of coordinates will correspond to an
*edge* in the graph, e.g.:

* Edge A - `LINESTRING(-77.08544159 38.93787003, -77.08544159 38.93793869)`
* Edge B - `LINESTRING(-77.08544159 38.93793869, -77.08545685 38.9380188)`
* Edge C - `LINESTRING(-77.08545685 38.9380188, -77.08548737 38.9381218)`

<Tip>
  After graph creation (and assuming the graph table was created), you
  can view each *edge's* details, including its respective WKT
  linestring, using [WMS](/content/admin/gadmin/data#gadmin-table-wms) and clicking an edge:

  <img src="https://mintlify.s3.us-west-1.amazonaws.com/kinetica/content/guides/shared/img/graph_concepts/edge_wms.png" alt="../img/graph_concepts/edge_wms.png" />
</Tip>

Each coordinate pair composing an *edge* is an implicit node:

<img src="https://mintlify.s3.us-west-1.amazonaws.com/kinetica/content/guides/shared/img/graph_concepts/edge_wms_nodes.png" alt="../img/graph_concepts/edge_wms_nodes.png" />

*Weights* in this graph, as mentioned previously, are an abstract cost
(distance, time, etc.) for traveling any roadway or footpath in the Washington,
D.C., area. *Weights* are particularly important when solving a graph. There are
two solver types presented in the tutorial below:

* `shortest_path` -- Find the shortest path between two points on a graph
* `multiple_routing` -- Find the quickest route between a source point and
  many destination points; also known as traveling salesman

Because there are no explicit *nodes* in the tutorial graph, source and
destination point(s) must be selected from any of the *edges* comprising the
Washington, D.C., road network. Otherwise, the graph will not be able to
traverse to the point and will result in a null solution.