Create SyncVars.md

docs/Classes/SyncVars.md

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+# SyncVars
+
+SyncVars are variables of scripts that inherit from NetworkBehaviour, which are synchronized from the server to clients. When a GameObject is spawned, or a new player joins a game in progress, they are sent the latest state of all SyncVars on networked objects that are visible to them. Use the `SyncVar` custom attribute to specify which variables in your script you want to synchronize, like this:
+
+```cs
+class Player : NetworkBehaviour
+{
+    [SyncVar]
+    int health;
+
+    public void TakeDamage(int amount)
+    {
+        if (!isServer)
+            return;
+
+        health -= amount;
+    }
+}
+```
+
+The state of SyncVars is applied to GameObjects on clients before OnStartClient() is called, so the state of the object is always up-to-date inside OnStartClient().
+
+SyncVars can be basic types such as integers, strings and floats. They can also be Unity types such as Vector3 and user-defined structs, but updates for struct SyncVars are sent as monolithic updates, not incremental changes if fields within a struct change. You can have up to 32 SyncVars on a single NetworkBehaviour script, including SyncLists (see next section, below).
+
+The server automatically sends SyncVar updates when the value of a SyncVar changes, so you do not need to track when they change or send information about the changes yourself.
+
+The [SyncVar hook](SyncVarHook) attribute can be used to specify a method to be called when the SyncVar changes value on the client.