Secret sharing is a technique for protecting sensitive data like cryptographic keys. This mechanism is used to distribute a secret value to a number of parties or users called shares. The shares are given to the parities or users involved in the group. These values have to be combined together to access the original values. Secret sharing is used in modern cryptography algorithms to reduce the risk in information leakage. Sharing a secret reduce the risk of compromising the value across several parties. Threshold or group oriented cryptography allows a group of users perform cryptographic operations such as encryption, decryption, signature etc. A trivial implementation of group-oriented cryptography can be achieved by concatenating secret sharing schemes and a single user cryptosystem. This book illustrate the basic RSA based Threshold Cryptography with numerical examples. This book is very useful for new research schollers working towards Threshold Cryptography. In this book, basic RSA based Threshold Cryptography is illustrated and stpes are explained with small numbers.