Applications accessing your accounts do so through routes with different regulatory status.
Regulated access
Authorised providers using permissioned interfaces.
Which is supervised and revocable.
Credential sharing
Services asking for your banking login.
Which should be refused.
Data use
What the provider does with the information.
Which the permission and privacy notice specify.
Reviewing permissions
Active authorisations listed by your bank.
Which are worth checking periodically.
The distinction worth insisting on
An authorised provider using a regulated interface never sees your banking credentials and can be switched off from your bank at any time.
Which is a fundamentally different arrangement from giving an app your login and password.
Any service asking for your banking credentials should be declined, regardless of how legitimate it appears, because the regulated alternative exists.
What providers may do with data
Uses stated in the permission and privacy notice.
Which vary considerably.
Data sold or shared
Aggregated financial data being commercially valuable.
Which some services monetise.
Revoking access
Permissions manageable from your bank.
A general note
Data protection and open banking rules differ by jurisdiction.
Why the plumbing is worth understanding
Most personal finance advice is about decisions: what to buy, what to save, what to avoid. Very little of it is about how the systems underneath actually work, and that is where a surprising amount of avoidable cost and avoidable risk sits.
Knowing that instant payments are hard to reverse changes how carefully you check a transfer. Knowing that deposit protection applies per licence rather than per brand changes where you hold savings. Knowing that card payments carry dispute rights changes how you pay for anything uncertain. None of those is a financial decision in the usual sense, and each of them matters more than most of the decisions people agonise over.
The pattern across all of this
Financial systems are built by institutions solving their own problems, and the consumer experience is a by-product. Fees are structured to be hard to compare. Rates are set on the assumption that most people will not move. Protections vary by mechanism in ways nobody explains at the point of use.
None of that is a conspiracy. It is what happens when complex systems are designed for the people running them, and the remedy is simply knowing where the differences are.
Where to find the reliable information
Financial regulators publish consumer guidance covering exactly this material, free and with nothing to sell. Payment scheme operators publish how their systems work. Deposit protection schemes publish their limits and which institutions they cover.
All of it is dry, none of it is promoted, and it is considerably more useful than the commercial content competing for the same attention.
A general note
Banking, payments, credit and insurance are regulated differently in every country, and the specifics here vary accordingly. This describes how these systems generally work and is not financial advice; anything with money attached warrants checking against the rules where you are.
The habits that follow from all this
Pay by card for anything you have not received yet. Check transfer details carefully because instant means instant. Verify unexpected requests through a number you found yourself rather than one you were given. Review your savings rate once a year and move if it is poor. Check your credit file annually for errors.
Five habits, none of them requiring any financial expertise, and between them they cover the majority of the situations where households lose money to something other than a spending decision.
Why nobody tells you this
There is no commercial incentive to explain how payment protections differ by method, because the explanation does not sell anything. There is a substantial commercial incentive to advertise financial products, which is why that content is everywhere and this content is not.
Regulators fill some of the gap with consumer guidance, and it is genuinely good and almost entirely unread. That is not a failure of the regulators so much as a consequence of it being unpromoted and competing against material with marketing budgets behind it.
What matters most
Of everything described here, two things account for most of the practical difference: how you pay for things, and whether you check anything once a year. Both are free and neither requires any decision more complicated than noticing.
Where to check the specifics
Financial regulators, payment scheme operators and deposit protection bodies publish the actual rules that apply where you live, and they are the authoritative source rather than any general description.
Rules in this area also change: reimbursement obligations, interchange caps, overdraft pricing and renewal pricing have all been reformed in several markets within recent years.
One closing point
Almost nothing described here is difficult, and almost none of it is explained at the point where it would be useful. That gap is the actual subject of all of it.