extra thin slot under my PCMCIA slot on my T61?

[n2ri]

is it for reading/writing credit cards? or what is it and how do I activate it? a credit card slips right in 3/4 of the way.

[RealBlackStuff]

It's for remote access authentication, such as explained here: https://technet.microsoft.com/en-us/lib ... 10%29.aspx

[n2ri]

oh like a key for corporate server laptops when you use one right?

[twistero]

Yes, it's a smart card reader. Examples of smart cards include chipped (EMV) credit cards, SIM cards used in phones, CAC cards for US military / defense personnel, Estonian ID card, etc.

Smart cards are often used for authentication, digital signature and encryption. A domain-joined Windows laptop may require a smart card for login; an E-resident of Estonia can sign a document with their ID card, and such signatures are legally equivalent to manual signatures; a DOD worker must plug in their CAC card in order to use webmail; and things like that.