But using lightning:input or lightning-input, we’re not allowed to add HTML tags under LABEL attribute.

So here are the work-arounds for AURA and LWC,

AURA

Component:

<aura:attribute name="chkTerms" type="Boolean"/>
<div>
    <input type="checkbox" id="terms" name="terms" value="{!v.chkTerms}" onchange="{!c.termsChanged}" ></input>
    <label for="terms"> Yes, by creating an account I agree to the <a href="#">Terms and Service.</a></label>
</div>

JS

termsChanged : function(cmp, event, helper){
    cmp.set("v.chkTerms", document.getElementById("terms").checked );
    //console.log(event.getSource().get("v.checked"));
    // the above didn't work except for `ui:input` or `lightning:input`
    console.log(cmp.get("v.chkTerms") ); 
}

LWC

HTML

<div class="slds-p-around_medium lgc-bg">
    <input type="checkbox" id="terms" name="authorize" onchange={handleCheckBoxChange} required="required"></input>
    <label for="terms" style="display: inline;" class="slds-form-element__label"> Yes, by creating an account I agree to the <a href="#">Terms and Service.</label>
</div>

JS

handleCheckBoxChange(event){        
    console.log('Authorized::'+event.target.checked);
    // Your Logic
}

Source
https://salesforce.stackexchange.com/questions/213749/lightninginput-checkbox-label-with-url

WHEN TO USE PLATFORM EVENTS?

1. Platform events are very useful when you want to communicate Salesforce with any external system.
2. Platform events are also used to communicate between two lightning applications.
3. Platform events are very useful when you want to communicate between two visualforce pages.

SUBSCRIPTION IN PLATFORM EVENT: 

1. Apex triggers receive event notifications.
2. write an “after insert” Apex trigger on the event object to subscribe to incoming events.
3. Triggers receive event notifications from various sources—whether they’re published through Apex or APIs.
4. Visualforce and Lightning component apps receive events through CometD.
5. CometD is a scalable HTTP-based event routing bus that uses an AJAX push technology pattern known as Comet.
6. In an external app, you subscribe to events using CometD as well.

CREATING PLATFORM EVENT OBJECT

Setup —-> Platform Event —-> New

Create Notification__e Platform event

Create a Lightning Component to display toast based on Platform event Creation

The lightning:empApi component provides access to methods for subscribing to a streaming channel and listening to event messages. All streaming channels are supported, including channels for platform events, PushTopic events, generic events, and Change Data Capture events. The lightning:empApi component uses a shared CometD connection.

To call the component’s methods, add the lightning:empApi component inside your custom component and assign an aura:id attribute to it.

Add this lightning component in lightning app utiliy bar

Once Platform event record get Created, A toast message is displayed

Source : https://sfdcrecipes.com/2019/04/13/platform-events-in-lightning-component/

Here is an example to use JS setTimeout function in AURA Component,

1. If set timeout modifies any attributes, use $A.callback-

window.setTimeout(
     $A.getCallback(function() {
          helper.hideSpinner(component, helper)
     }), 500
);

2. As per setTimeout documentation, use any one of the following if calling function doesn’t modifies any attributes:

window.setTimeout(function(){ helper.hideSpinner(component, helper)}, 500);
// or
window.setTimeout(helper.hideSpinner, 500, component, helper);

Sources,

https://github.com/edelrabe/Salesforce-Recipes/wiki/setTimeout-in-Lightning-Component
https://salesforce.stackexchange.com/questions/206017/lightning-component-error-for-settimeout-bind-must-be-called-on-a-function/206018

Salesforce Files had been introduced with replacement of Attachment/Document object and with some great features like version controlling, sharing, preview and what not.

We used to use Attachment/Document object for file hosting like images and pdf (specially on Classic).

And if we needed to use that image on any VF page or AURA component, we simply use record id and below code to generate url:

imageURL='/servlet/servlet.FileDownload?file=<document_name>';

But with Salesforce Files object, we have to maintain 3 records in 3 different objects “ContentDocument, ContentVersion, ContentLink” and for Public Link =”ContentDistribution”.

If you’re going to use your custom component/vf page internally, then you can use below code:

imageURL='/sfc/servlet.shepherd/document/download/<YOUR FILE ID>';

But when you need it to be visible for guest users, then you’ll need to generate PUBLIC URL which you can do manually.

Generating Public Link:

Code below will generate public url automatically. You can use this code on a trigger on Files object

ContentDocumentLink cdl = [select contentdocument.id, contentdocument.title, contentdocument.filetype from contentdocumentlink where linkedentityid = '<Opportunity Id>'];
ContentVersion cv = [select id from contentversion where contentdocumentid = :cdl.contentdocument.id];
ContentDistribution cd = new ContentDistribution();
cd.Name = 'Test';
cd.ContentVersionId = cv.id;
cd.PreferencesAllowViewInBrowser= true;
cd.PreferencesLinkLatestVersion=true;
cd.PreferencesNotifyOnVisit=false;
cd.PreferencesPasswordRequired=false;
cd.PreferencesAllowOriginalDownload= true;
insert cd;

<img> tag URL Generation

Now the ContentDistribution object will store the public URL but it’ll contain the preview and we cannot use it as <img src> tag. Therefore we need actual image URL which you can get manually by properties of image and click “Copy image address”.

Below public link will be generated by code

https://<domain>.my.salesforce.com/sfc/p/#q00000000sNA/a/q00000008a0b/6woo3x9YQNR7vTXR2oOOmknAOjpytHMEnZc2nGQ3F54

Below correct link we need to use as <img> tag.

https://<domain>--c.documentforce.com/sfc/dist/version/renditionDownload?rendition=ORIGINAL_Jpg&versionId=068q0000000RAdv&operationContext=DELIVERY&contentId=05Tq0000001RiQf&page=0&d=/a/q00000008a0b/6woo3x9YQNR7vTXR2oOOmknAOjpytHMEnZc2nGQ3F54&oid=<organization Id>&dpt=null&viewId=

Use following code to convert the public url to actual url we need.

List<Domain> domainList = [SELECT Domain FROM Domain];
                String domainString = domainList[0].Domain;
                String domainNameSubstring = domainString.substringBefore('.');
                String secondPart = domainNameSubstring.substringBefore('-');
                String firstPart = domainNameSubstring.substringAfter('-');
                String customDomainName = 'https://' + firstPart + '--' + secondPart + '--c.documentforce.com';

Happy coding!

Sources :
https://developer.salesforce.com/forums/?id=9060G0000005kE0QAI
https://salesforce.stackexchange.com/questions/236980/how-to-display-image-in-a-lightning-component
https://salesforce.stackexchange.com/questions/187424/display-image-which-is-stored-in-files