Use of String (upper case 'S') vs. string (lower case 's')

It seems to me that the 'string' C# keyword is used interchangeably with the System.String class.

I believe these are different, and that if a method signature returns a 'string' type, that would be different than a System.String struct or class instance.

Are the various uses of String vs. string consistent and correct in every case on the page?

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* ID: dc60ab93-74c9-2404-67dd-1dc9017c0dc9
* Version Independent ID: feaee2f1-85dc-7793-b693-853e95f54f39
* Content: [String.TrimStart Method (System)](https://docs.microsoft.com/en-us/dotnet/api/system.string.trimstart?view=netframework-4.7.2)
* Content Source: [xml/System/String.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System/String.xml)
* Product: **dotnet-api**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**