diff --git a/arithmetic_analysis/README.md b/arithmetic_analysis/README.md
new file mode 100644
index 000000000..45cf321eb
--- /dev/null
+++ b/arithmetic_analysis/README.md
@@ -0,0 +1,7 @@
+# Arithmetic analysis
+
+Arithmetic analysis is a branch of mathematics that deals with solving linear equations.
+
+* <https://en.wikipedia.org/wiki/System_of_linear_equations>
+* <https://en.wikipedia.org/wiki/Gaussian_elimination>
+* <https://en.wikipedia.org/wiki/Root-finding_algorithms>
diff --git a/audio_filters/README.md b/audio_filters/README.md
new file mode 100644
index 000000000..4419bd8bd
--- /dev/null
+++ b/audio_filters/README.md
@@ -0,0 +1,9 @@
+# Audio Filter
+
+Audio filters work on the frequency of an audio signal to attenuate unwanted frequency and amplify wanted ones.
+They are used within anything related to sound, whether it is radio communication or a hi-fi system.
+
+* <https://www.masteringbox.com/filter-types/>
+* <http://ethanwiner.com/filters.html>
+* <https://en.wikipedia.org/wiki/Audio_filter>
+* <https://en.wikipedia.org/wiki/Electronic_filter>
diff --git a/backtracking/README.md b/backtracking/README.md
new file mode 100644
index 000000000..d4975dfb5
--- /dev/null
+++ b/backtracking/README.md
@@ -0,0 +1,8 @@
+# Backtracking
+
+Backtracking is a way to speed up the search process by removing candidates when they can't be the solution of a problem.
+
+* <https://en.wikipedia.org/wiki/Backtracking>
+* <https://en.wikipedia.org/wiki/Decision_tree_pruning>
+* <https://medium.com/@priyankmistry1999/backtracking-sudoku-6e4439e4825c>
+* <https://www.geeksforgeeks.org/sudoku-backtracking-7/>
diff --git a/bit_manipulation/README.md b/bit_manipulation/README.md
index e5f82a270..3f5e028be 100644
--- a/bit_manipulation/README.md
+++ b/bit_manipulation/README.md
@@ -1,6 +1,11 @@
-* https://docs.python.org/3/reference/expressions.html#binary-bitwise-operations
-* https://docs.python.org/3/reference/expressions.html#unary-arithmetic-and-bitwise-operations
-* https://docs.python.org/3/library/stdtypes.html#bitwise-operations-on-integer-types
-* https://wiki.python.org/moin/BitManipulation
-* https://wiki.python.org/moin/BitwiseOperators
-* https://www.tutorialspoint.com/python3/bitwise_operators_example.htm
+# Bit manipulation
+
+Bit manipulation is the act of manipulating bits to detect errors (hamming code), encrypts and decrypts messages (more on that in the 'ciphers' folder) or just do anything at the lowest level of your computer.
+
+* <https://en.wikipedia.org/wiki/Bit_manipulation>
+* <https://docs.python.org/3/reference/expressions.html#binary-bitwise-operations>
+* <https://docs.python.org/3/reference/expressions.html#unary-arithmetic-and-bitwise-operations>
+* <https://docs.python.org/3/library/stdtypes.html#bitwise-operations-on-integer-types>
+* <https://wiki.python.org/moin/BitManipulation>
+* <https://wiki.python.org/moin/BitwiseOperators>
+* <https://www.tutorialspoint.com/python3/bitwise_operators_example.htm>
diff --git a/boolean_algebra/README.md b/boolean_algebra/README.md
new file mode 100644
index 000000000..45969c855
--- /dev/null
+++ b/boolean_algebra/README.md
@@ -0,0 +1,7 @@
+# Boolean Algebra
+
+Boolean algebra is used to do arithmetic with bits of values True (1) or False (0).
+There are three basic operations: 'and', 'or' and 'not'.
+
+* <https://en.wikipedia.org/wiki/Boolean_algebra>
+* <https://plato.stanford.edu/entries/boolalg-math/>