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docs/faq.md

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+# FAQ
+### Do I need to use mxisd if I run a Homeserver?
+No, but it is recommended, even if you don't use any backends or integration.
+
+In its default configuration, mxisd will talk to the central Matrix Identity servers and use other federated public
+servers when performing queries, giving you access to at least the same information as if you were not running it.
+
+It will also give your users a choice to make their 3PIDs available publicly, ensuring they are made aware of the
+privacy consequences, which is not the case with the central Matrix.org servers.
+
+So mxisd is like your gatekeeper and guardian angel. It does not change what you already know, just adds some nice
+simple features on top of it.
+
+### I already use the synapse LDAP3 auth provider, why should I care about mxisd?
+The [synapse LDAP3 auth provider](https://github.com/matrix-org/matrix-synapse-ldap3) is not longer maintained and
+only handles on specific flow: validate credentials at login.
+
+It does not:
+- Auto-provision user profiles
+- Integrate with Identity management
+- Integrate with Directory searches
+- Protect you against the username case sensitivites issues in synapse
+
+mxisd is a replacement and enhancement of it, offering coherent results in all areas, which LDAP3 auth provider
+does not.
+
+### Sydent is the official Identity server implementation of the Matrix team, why not use that?
+You can, but [sydent](https://github.com/matrix-org/sydent):
+- [should not be used and/or self-hosted](https://github.com/matrix-org/sydent/issues/22)
+- is not meant to be linked to a specific Homeserver / domain
+- cannot handle federation or proxy lookups, effectively isolating your users from the rest of the network
+- forces you to duplicate all your identity data, so people can be found by 3PIDs
+- forces users to enter all their emails and phone numbers manually in their profile
+
+So really, you should go with mxisd.
+
+### Will I loose access to the central Matrix.org/Vector.im Identity data if I use mxisd?
+In its default configuration, mxisd act as a proxy to Matrix.org/Vector.im. You will have access to the same data and
+behaviour than if you were using them directly. There is no downside in using mxisd with the default configuration.
+
+mxisd can also be configured not to talk to the central Identity servers if you wish.
+
+### I'm not sure I understand what an "Identity server" is supposed to be or do
+The current Identity service API is more a placeholder, as the Matrix devs did not have time so far to really work on
+what they want to do with that part of the ecosystem. Therefore, "Identity" is a misleading word currently.  
+Given the scope of the current Identity Service API, it would be best called "Invitation service".
+
+Because the current scope is so limited and no integration is done with the Homeserver, there was a big lack of features
+for groups/corporations/organisation. This is where mxisd comes in.
+
+mxisd implements the Identity Service API and also a set of features which are expected by regular users, truly living
+up to its "Identity server" name.
+
+### So mxisd is just a big hack! I don't want to use non-official features!
+mxisd primary concern is to always be compatible with the Matrix ecosystem and the Identity service API.  
+Whenever the API will be updated and/or enhanced, mxisd will follow, remaining 100% compatible with the ecosystem.
+
+We also directly talk with the Matrix developers to ensure all features we implement have their approval, and that we
+are in line with their vision of Identity management within the Matrix ecosystem.
+
+Therefore, using mxisd is a safe choice. It will be like using the central Matrix.org Identity servers, yet not closing
+the door to very nice enhancements and integrations.
+
+### Should I use mxisd if I don't host my own Homeserver?
+No