Router Link
routerLink with brackets and none - simple explanation.
The difference between routerLink= and [routerLink] is mostly like relative and absolute path.
Similar to a href you may want to navigate to ./about.html or https://your-site.com/about.html.
When you use without brackets then you navigate relative and without params;
my-app.com/dashboard/client
"jumping" from my-app.com/dashboard to my-app.com/dashboard/client
<a routerLink="client/{{ client.id }}" .... rest the same
When you use routerLink with brackets then you execute app to navigate absolute and you can add params how is the puzzle of your new link
first of all it will not include the "jump" from dashboard/ to dashboard/client/client-id and bring you data of client/client-id which is more helpful for EDIT CLIENT
<a [routerLink]="['/client', client.id]" ... rest the same
The absolute way or brackets routerLink require additional set up of you components and app.routing.module.ts
The code without error will "tell you more/what is the purpose of []" when you make the test. Just check this with or without []. Than you may experiments with selectors which - as mention above - helps with dynamics routing.
See whats the routerLink construct