ublock is off by default and only the sites you specify will be blocked.

[cuckoojohn]

Prerequisites

• I verified that this is not a filter issue
  • Filter issues MUST be reported at filter issue tracker
• This is not a support issue or a question
  • Support issues and questions are handled at /r/uBlockOrigin
• I performed a cursory search of the issue tracker to avoid opening a duplicate issue
  • Your issue may already be reported.
• I tried to reproduce the issue when...
  • uBlock Origin is the only extension
  • uBlock Origin with default lists/settings
  • using a new, unmodified browser profile
• I am running the latest version of uBlock Origin
• I checked the documentation to understand that the issue I report is not a normal behavior

Description

[Description of the bug or feature]

A specific URL where the issue occurs

[A specific URL is MANDATORY for issue happening on a web page, even if it happens "everywhere"]

Steps to Reproduce

1. [First Step]
2. [Second Step]
3. [and so on...]

Expected behavior:

[What you expected to happen]

Actual behavior:

[What actually happened]

Your environment

• uBlock Origin version:
• Browser Name and version:
• Operating System and version:

https://github.com/gorhill/uBlock/wiki/How-to-whitelist-a-web-site#disabling-filtering-temporarily-or-by-default-blacklist-mode

[gorhill]

I will just quote what I just answered on Reddit:

With uBO the default and sane assumption is that the internet is hostile and given this, disabling content blocking everywhere by default would be incompatible with uBO.