When APIs are created via Api Gateway, the APIs need to deployed before it can be used. In Api Gateway, the api is deployed in stages. If a stage is not already created, a stage needs to be created during deployment or by navigating to stages from the left menu.
To deploy an api, click on "Deploy API" from the Actions dropdown.
Then select the deployment stage and hit deploy.
Once deployed, the stage editor is displayed where additional settings like caching, logging can be set and stage variables can also be set.
Now the api is deployed and the url is available from "Invoke URL" section as in the above image. The api can be tested using this url. The default settings of the api can be obtained from the default stage settings or it can be modified - the cloudwatch logs, caching and throttling settings can be changed for the particular api.