Note there are way more APIs than this but the exam is OLD.
Bulk API
REST based
Aysnchronous
Version 1 (OLD) and Version 2
Large Data Volumes
For Data Migrations
Query, Insert, Update, Upsert and Delete
Create a Job
Send data in batches
check status of batches
retrieve the result for each batch
Close the job
Chatter REST API / Connect API
The Chatter API became the Connect API in Summer '20 https://releasenotes.docs.salesforce.com/en-us/summer20/release-notes/rn_chatter_api.htm
Chatter Feed
Users
Groups
Followers
Data is structured for rendering on websites and mobile devices.
Returned information is localized to the user's time zone and language.
Changed values that are tracked in a feed are returned as value-pair representations.
Rate limiting for Chatter REST API is per user, per application, per hour. The rate limiting for SOAP API and REST API is by organization. When you exceed the rate limit, all Connect REST API resources return a 503 Service Unavailable error code.
If needed, extract an ID from the REST API and use it in requests to Chatter REST API.
Metadata API
the metadata of the Org
Streaming API
Pub / Sub model
Subscribe to a channel
No need for polling
Broadcast changes
Concurrent limits (No. of long running calls) and total limits
Email Service
Process Contents, Headers and Attachments of Inbound Email
Messaging.InboundEmailHandler
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