In this example, nothing really. The exact param comes into play when you have multiple paths that have similar names:

For example, imagine we had a Users component that displayed a list of users. We also have a CreateUser component that is used to create users. The url for CreateUsers should be nested under Users. So our setup could look something like this:

<Switch>
  <Route path="/users" component={Users} />
  <Route path="/users/create" component={CreateUser} />
</Switch>

Now the problem here, when we go to http://app.com/users the router will go through all of our defined routes and return the FIRST match it finds. So in this case, it would find the Users route first and then return it. All good.

But, if we went to http://app.com/users/create, it would again go through all of our defined routes and return the FIRST match it finds. React router does partial matching, so /users partially matches /users/create, so it would incorrectly return the Users route again!

The exact param disables the partial matching for a route and makes sure that it only returns the route if the path is an EXACT match to the current url.

So in this case, we should add exact to our Users route so that it will only match on /users:

<Switch>
  <Route exact path="/users" component={Users} />
  <Route path="/users/create" component={CreateUser} />
</Switch>

The docs explain exact in detail and give other examples.

In short, if you have multiple routes defined for your app's routing, enclosed with Switch component like this;

<Switch>

  <Route exact path="/" component={Home} />
  <Route path="/detail" component={Detail} />

  <Route exact path="/functions" component={Functions} />
  <Route path="/functions/:functionName" component={FunctionDetails} />

</Switch>

Then you have to put exact keyword to the Route which it's path is also included by another Route's path. For example home path / is included in all paths so it needs to have exact keyword to differentiate it from other paths which start with /. The reason is also similar to /functions path. If you want to use another route path like /functions-detail or /functions/open-door which includes /functions in it then you need to use exact for the /functions route.

Take a look here: https://reacttraining.com/react-router/core/api/Route/exact-bool

exact: bool

When true, will only match if the path matches the location.pathname exactly.

**path**    **location.pathname**   **exact**   **matches?**

/one        /one/two                true        no
/one        /one/two                false       yes